U.S. patent application number 13/576786 was filed with the patent office on 2012-12-06 for expandable film, dicing film, and method of producing semiconductor device.
This patent application is currently assigned to Mitsui Chemicals, Inc.. Invention is credited to Eiji Hayashishita, Setsuko Oike, Katsutoshi Ozaki, Mitsuru Sakai.
Application Number | 20120309170 13/576786 |
Document ID | / |
Family ID | 45892358 |
Filed Date | 2012-12-06 |
United States Patent
Application |
20120309170 |
Kind Code |
A1 |
Hayashishita; Eiji ; et
al. |
December 6, 2012 |
EXPANDABLE FILM, DICING FILM, AND METHOD OF PRODUCING SEMICONDUCTOR
DEVICE
Abstract
To provide an olefinic expandable substrate and a dicing film
that exhibits less contamination characteristics, high
expandability without necking, which cannot be achieved by
conventional olefinic expandable substrates. In order to achieve
the object, an expandable film comprises a 1-butene-.alpha.-olefin
copolymer (A) having a tensile modulus at 23.degree. C. of 100 to
500 MPa and a propylenic elastomer composition (B) comprising a
propylene-.alpha.-olefin copolymer (b1) and having a tensile
modulus at 23.degree. C. of 10 to 50 MPa, wherein the amount of the
component (B) is 30 to 70 weight parts relative to 100 weight parts
in total of components (A) and (B).
Inventors: |
Hayashishita; Eiji;
(Nagoya-shi, JP) ; Ozaki; Katsutoshi; (Nagoya-shi,
JP) ; Sakai; Mitsuru; (Kisarazu-shi, JP) ;
Oike; Setsuko; (Yokohama-shi, JP) |
Assignee: |
Mitsui Chemicals, Inc.
Minato-ku
JP
|
Family ID: |
45892358 |
Appl. No.: |
13/576786 |
Filed: |
September 28, 2011 |
PCT Filed: |
September 28, 2011 |
PCT NO: |
PCT/JP2011/005466 |
371 Date: |
August 2, 2012 |
Current U.S.
Class: |
438/464 ;
257/E21.599; 428/212; 428/343; 525/240 |
Current CPC
Class: |
C08J 5/18 20130101; C09J
7/29 20180101; Y10T 156/1052 20150115; C09J 2203/326 20130101; B32B
2274/00 20130101; Y10T 428/28 20150115; C08J 2323/20 20130101; C09J
2301/162 20200801; B32B 27/308 20130101; C08J 2323/16 20130101;
C09J 7/241 20180101; B32B 27/32 20130101; H01L 21/6836 20130101;
B32B 27/08 20130101; B32B 2270/00 20130101; B32B 2457/14 20130101;
C09J 2423/006 20130101; B32B 2405/00 20130101; Y10T 428/24942
20150115 |
Class at
Publication: |
438/464 ;
428/343; 428/212; 525/240; 257/E21.599 |
International
Class: |
H01L 21/78 20060101
H01L021/78; C08L 23/20 20060101 C08L023/20; C08L 23/14 20060101
C08L023/14; C09J 7/02 20060101 C09J007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 2010 |
JP |
2010-222046 |
Apr 1, 2011 |
JP |
2011-082113 |
Claims
1. An expandable film comprising: a 1-butene-.alpha.-olefin
copolymer (A) having a tensile modulus at 23.degree. C. of 100 to
500 MPa; and a propylenic elastomer composition (B) comprising a
propylene-.alpha.-olefin copolymer (b1) and having a tensile
modulus at 23.degree. C. of 8 to 500 MPa, wherein an amount of the
composition (B) is in the range of 30 to 70 weight parts relative
to 100 weight parts in total of the components (A) and (B).
2. The expandable film according to claim 1, wherein the propylenic
elastomer composition (B) has a tensile modulus at 23.degree. C. of
10 to 50 MPa.
3. The expandable film according to claim 1, wherein the propylenic
elastomer composition (B) contains 1 to 70 weight parts of a
polypropylene (b2) relative to 100 weight parts of the propylenic
elastomer composition (B).
4. The expandable film according to claim 3, wherein the propylenic
elastomer composition (B) contains 5 to 20 weight parts of the
polypropylene (b2) relative to 100 weight parts of the propylenic
elastomer composition (B).
5. A dicing film comprising: a substrate layer comprising the
expandable film according to claim 1 and an adhesive layer, wherein
the adhesive layer is an outermost layer of the dicing film, and
the adhesive layer has an adhesive force of 0.1 to 10 N/25 mm
measured in accordance with JIS Z0237 when the dicing film is
peeled off from a surface of a stainless steel-304-BA plate 60
minutes after the adhesive layer is bonded to the surface of the
stainless steel-304-BA plate.
6. The dicing film according to claim 5, wherein the substrate
layer and the adhesive layer each have an MFR of 1 to 20 g/10 min,
the MFR being measured at 230.degree. C. in accordance with ASTM
D1238.
7. A dicing film comprising: a substrate layer comprising the
expandable film according to claim 1; and an intermediate layer,
wherein the intermediate layer satisfies the relation
E(60)/E(25)<0.1 where E(25) is a tensile modulus at 25.degree.
C. and E(60) is a tensile modulus at 60.degree. C., and the tensile
modulus at 25.degree. C. is in the range of 1 to 10 MPa.
8. The dicing film according to claim 5, further comprising an
intermediate layer between the substrate layer and the adhesive
layer, wherein the intermediate layer satisfies the relation
E(60)/E(25)<0.1 where E(25) is a tensile modulus at 25.degree.
C. and E(60) is a tensile modulus at 60.degree. C., and the tensile
modulus at 25.degree. C. is in the range of 1 to 10 MPa.
9. The dicing film according to claim 7, wherein the intermediate
layer contains an olefinic copolymer.
10. The dicing film according to claim 7, wherein the intermediate
layer has a density of 800 to 890 kg/m.sup.3.
11. The dicing film according to claim 7, wherein the dicing film
is for bonding on at least one surface of a semiconductor wafer,
the surface having irregularities, and the intermediate layer has a
thickness larger than the height of the irregularities of the
semiconductor wafer.
12. A method of manufacturing a semiconductor device, comprising:
bonding the dicing film according to claim 5 to a semiconductor
wafer with the adhesive layer of the dicing film; dicing the
semiconductor wafer into semiconductor chips; and expanding the
dicing film and picking up the semiconductor chips.
13. A method of manufacturing a semiconductor device, comprising:
bonding the dicing film according to claim 8 to a semiconductor
wafer at a temperature of 40 to 80.degree. C. and a pressure of 0.3
to 0.5 MPa with the adhesive layer of the dicing film; dicing the
semiconductor wafer into semiconductor chips; and expanding the
dicing film and picking up the semiconductor chips.
Description
TECHNICAL FIELD
[0001] The present invention relates to an expandable film and a
dicing film including the expandable film. The dicing film is
useful as an adhesive sheet that is bonded to a front or rear
surface of a semiconductor wafer in a process involving dicing the
wafer into individual dice (chips) and automatically picking up the
chips for recovery. The present invention also relates to a method
of manufacturing a semiconductor device using the dicing film and a
semiconductor device produced by the method.
BACKGROUND ART
[0002] In a process of manufacturing semiconductor devices, a
silicon wafer having a predetermined circuit pattern is diced into
individual chips with a rotating round blade. A common way during
the process involves bonding the silicon wafer to an adhesive film,
dicing the silicon wafer into individual chips, stretching the
adhesive film in lateral and longitudinal directions to expand the
chip-to-chip distance, and picking up the chips (see Patent
Literature 1). In recent years, laser ablation dicing of
semiconductor substrates has attract attention because this dicing
technique can process the substrates with high precision without
thermal damaging compared to blade dicing. A proposed process in
this technique involves fixing a work onto a dicing sheet and
dicing the work with laser light (refer to PTL 2).
[0003] A manufacturing process of light emitting diodes (LEDs)
using materials such as sapphire, gallium and arsenic yields
individual chips of several hundred micrometers in size and
therefore requires expansion of the chip-to-chip distance through
sufficient stretching of an adhesive dicing film. A disadvantage of
LED substrates that are fragile compared to silicon is that the
dice are subjected to chipping during the conventional blade
dicing. There has been a demand in the art for an expandable dicing
substrate that is suitable for laser ablation dicing--a technique
that is less damaging to substrates--and provides less
contamination and sufficient expandability.
[0004] A requirement for an expandable dicing substrate is uniform
stretching of the entire substrate without necking during a
stretching operation. Necking results in partial expansion at the
peripheries of the film with insufficient expansion in a central
region of the film, and thus insufficient separation of chips in
the central region. A commonly used expandable dicing substrate is
soft vinyl chloride which barely undergoes necking (see, e.g.,
Patent Literature 3). A disadvantage of the expandable dicing
substrate is contamination of the wafer by transfer of plasticizers
contained in soft vinyl chloride through the adhesive layer (see
Patent Literature 4). An expandable substrate composed of
plasticizer-free thermoplastic polyolefin has been proposed as a
substitution for vinyl chloride. Unfortunately, such an expandable
substrate exhibits poor expansion and significant necking compared
to vinyl chloride, resulting in an insufficient chip-to-chip
distance, although it can reduce contamination of wafers.
[0005] Patent Literature 1 discloses a dicing film including a
substrate and an adhesive layer, the substrate being composed of a
thermoplastic resin having rubber elasticity and an ethylenic
resin. A possible concern of the dicing film is necking, despite
reduced contamination of a wafer.
[0006] Patent Literature 5 discloses a dicing film including an
expandable substrate of a terpolymer (ionomer resin) composed of
ethylene, acrylic acid, and alkyl acrylate ester as components.
[0007] Patent Literature 6 discloses a dicing film including an
expandable substrate that is composed of a semi-compatible or
non-compatible polymer blend containing a highly crystalline
olefinic resin and a lowly crystalline olefin resin and that barely
generates linty dust during dicing. Exemplified lowly crystalline
olefinic resins are low-density polyethylene, random polypropylene
copolymer, and ethylene-vinyl acetate copolymer.
[0008] Patent Literatures 7 to 9 each disclose a dicing film
including an expandable substrate that is composed of propylene and
ethylene, and/or .alpha.-olefinic thermoplastic elastomer having
four to eight carbon atoms and that barely generates linty dust
during dicing. According to the description, the .alpha.-olefinic
thermoplastic elastomer may contain additives such as low-density
polyethylene, polypropylene, polybutene, and polyesters.
CITATION LIST
Patent Literature
[0009] [PTL 1] Japanese Patent Application Laid-Open No. 02-215528
[0010] [PTL 2] Japanese Patent Application Laid-Open No.
2002-343747 [0011] [PTL 3] Japanese Patent Application Laid-Open
No. 2002-235055 [0012] [PTL 4] Japanese Patent Application
Laid-Open No. 59-74178 [0013] [PTL 5] Japanese Patent No. 3845129
[0014] [PTL 6] Japanese Patent No. 3340979 [0015] [PTL 7] Japanese
Patent No. 3443110 [0016] [PTL 8] Japanese Patent No. 3984075
[0017] [PTL 9] Japanese Patent No. 3984076
SUMMARY OF INVENTION
Technical Problem
[0018] Although the dicing film disclosed in Patent Literature 5
exhibits high expandability and less necking, foreign materials
inherent in polymerization may remain in the dicing film. Laser
dicing may cause the foreign materials to scatter laser light. The
dicing film disclosed in Patent Literature 6 exhibits insufficient
expandability and therefore is prone to rupture during stretching,
which raises a concern of wafer damaging during expansion. In the
dicing films disclosed in Patent Literatures 7 to 9, the preferred
thermoplastic elastomer content is 80 weight percent or more, which
content may cause insufficient expansion.
[0019] An object of the present invention, in view of the problems
described above, is to provide a low-contamination olefinic
expandable substrate (expandable film) and a dicing film including
the substrate. Another object of the present invention is to
provide an olefinic expandable substrate that has exhibits high
expandability, which has been insufficient in conventional olefinic
expandable substrates, as well as less necking, and a dicing film
including the substrate.
Solution to Problem
[0020] The present inventors have intensively studied in order to
develop an expandable substrate exhibiting high expandability, less
necking, and low contamination. As a result, the inventors have
established that the object can be achieved when the following
conditions are satisfied, and completed the present invention.
[0021] 1) The substrate contains (A) a 1-butene-.alpha.-olefin
copolymer having a tensile strength of 100 to 500 MPa; and
[0022] 2) The substrate contains (B) a propylenic elastomer
composition containing (b1) a propylene/butene-.alpha.-olefin
copolymer and (b2) polypropylene, the composition (B) having a
tensile strength of 8 to 500 MPa;
[0023] 3) The amount of the composition (B) is in the range of 30
to 70 weight parts relative to 100 weight parts in total of the
components (A) and (B).
[0024] A substrate containing only the component (A) exhibits
insufficient expandability and is likely to exhibit necking,
whereas a substrate containing only the component (B) exhibits
insufficient expandability and low tensile strength, resulting in
poor handling performance. Even when a substrate contains both the
components (A) and (B), a component (A) content exceeding 70 weight
parts relative to 100 weight parts in total of the components (A)
and (B) causes necking to more likely to occur, whereas a component
(B) content exceeding 70 weight parts relative to 100 weight parts
in total of the components (A) and (B) results in low expandability
and thus poor handling performance. In contrast, satisfying the
requirements 1) to 3) leads to an expandable substrate that
exhibits high expandability, less necking, low contamination, and
high handling performance.
[0025] A first aspect of the present invention relates to an
expandable film
[0026] [1] A expandable film including: (A) a
1-butene-.alpha.-olefin copolymer having a tensile strength of 100
to 500 MPa at 23.degree. C.; and (B) a propylenic elastomer
composition containing (b1) a propylene/butene-.alpha.-olefin
copolymer having a tensile strength of 8 to 500 MPa at 23.degree.
C., wherein an amount of the component (B) is in the range of 30 to
70 weight parts relative to 100 weight parts in total of the
components (A) and (B).
[0027] [2] The expandable film according to [1], wherein the
propylenic elastomer composition (B) has a tensile strength at
23.degree. C. of 10 to 50 MPa.
[0028] [3] The expandable film according to [1] or [2], wherein the
propylenic elastomer composition (B) contains 1 to 70 weight parts
of a polypropylene (b2) relative to 100 weight parts of the
propylenic elastomer composition (B).
[0029] [4] The expandable film according to [3], wherein the
propylenic elastomer composition (B) contains 5 to 20 weight parts
of the polypropylene (b2) relative to 100 weight parts of the
propylenic elastomer composition (B).
[0030] A second aspect of the present invention relates to a dicing
film including an expandable film and a method of manufacturing a
semiconductor device.
[0031] [5] A dicing film including: a substrate layer and an
adhesive layer, the substrate layer including the expandable film
of any one of [1] to [4], wherein the adhesive layer is an
outermost layer of the dicing film and has an adhesive force of 0.1
to 10 N/25 mm measured in accordance with JIS Z0237 when the dicing
film is peeled off from a surface of a stainless steel-304-BA plate
60 minutes after the adhesive layer is bonded to the surface of the
stainless steel-304-BA plate.
[0032] [6] The dicing film according to [5], wherein the MFR of the
substrate layer at 230.degree. C. and the MFR of the adhesive layer
at 230.degree. C. which are measured in accordance with ASTM D1238
are both in the range of 1 to 20 g/10 min.
[0033] [7] A dicing film including: a substrate layer and an
intermediate layer, the substrate layer including the expandable
film of any one of [1] to [4], wherein the intermediate layer
satisfies the relation E(60)/E(25)<0.1 where E(25) is a tensile
modulus E(25) at 25.degree. C. and E(60) is a tensile modulus at
60.degree. C., and the tensile modulus at 25.degree. C. is in the
range of 1 to 10 MPa.
[0034] [8] The dicing film according to [5], further including an
intermediate layer between the substrate layer and the adhesive
layer, wherein the intermediate layer satisfies the relation
E(60)/E(25)<0.1 where E(25) is a tensile modulus at 25.degree.
C. and E(60) is a tensile modulus at 60.degree. C., and the tensile
modulus E(25) at 25.degree. C. is in the range of 1 to 10 MPa.
[0035] [9] The dicing film according to [7] or [8], wherein the
intermediate layer contains an olefinic copolymer.
[0036] [10] The dicing film according to any one of [7] to [9],
wherein the intermediate layer has a density of 800 to 890
kg/m.sup.3.
[0037] [11] The dicing film according to any one of [7] to [10],
wherein the dicing film is for bonding on at least one surface of a
semiconductor wafer, the surface having irregularities on at least
one side, and the intermediate layer has a thickness larger than
the height of the irregularities of the semiconductor wafer.
[0038] [12] A method of manufacturing a semiconductor device
including: bonding the dicing film according to [5] to a
semiconductor wafer with the adhesive layer of the dicing film;
dicing the semiconductor wafer into semiconductor chips; and
expanding the dicing film and picking up the semiconductor
chips.
[0039] [13] A method of manufacturing a semiconductor-manufacturing
device including: bonding the dicing film according to [8] to a
semiconductor wafer with the adhesive layer of the dicing film at a
temperature of 40 to 80.degree. C. and a pressure of 0.3 to 0.5
MPa; dicing the semiconductor wafer into semiconductor chips; and
expanding the dicing film and picking up the semiconductor
chips.
Advantageous Effects of Invention
[0040] The present invention provides an olefinic expandable
substrate (expandable film) having low contamination and high
expandability, which is insufficient in conventional olefinic
expandable substrates, with less necking, and provides a dicing
film including the substrate.
BRIEF DESCRIPTION OF DRAWINGS
[0041] FIG. 1A is a sectional TEM image parallel to the MD
direction of a substrate layer of an expandable film according to
an embodiment of the present invention;
[0042] FIG. 1B is a sectional TEM image parallel to the TD
direction of a substrate layer of an expandable film according to
an embodiment of the present invention;
[0043] FIG. 2 is a cross-sectional view schematically illustrating
an embodiment of a dicing film of the present invention;
[0044] FIG. 3 is a cross-sectional view schematically illustrating
another embodiment of the dicing film of the present invention;
[0045] FIG. 4A illustrates part of a method of manufacturing a
semiconductor device using a dicing film according to an embodiment
of the present invention;
[0046] FIG. 4B illustrates part of a method of manufacturing a
semiconductor device using a dicing film according to an embodiment
of the present invention;
[0047] FIG. 4C illustrates part of a method of manufacturing a
semiconductor device using a dicing film according to an embodiment
of the present invention;
[0048] FIG. 4D illustrates part of a method of manufacturing a
semiconductor device using a dicing film according to an embodiment
of the present invention;
[0049] FIG. 4E illustrates part of a method of manufacturing a
semiconductor device using a dicing film according to an embodiment
of the present invention;
[0050] FIG. 5A illustrates part of a method of manufacturing a
semiconductor device using a dicing film according to another
embodiment of the present invention;
[0051] FIG. 5B illustrates part of a method of manufacturing a
semiconductor device using a dicing film according to another
embodiment of the present invention;
[0052] FIG. 5C illustrates part of a method of manufacturing a
semiconductor device using a dicing film according to another
embodiment of the present invention;
[0053] FIG. 5D illustrates part of a method of manufacturing a
semiconductor device using a dicing film according to another
embodiment of the present invention;
[0054] FIG. 5E illustrates part of a method of manufacturing a
semiconductor device using a dicing film according to another
embodiment of the present invention;
[0055] FIG. 6A includes a top view and a side view illustrating a
method of expanding a laminate film according to an embodiment;
and
[0056] FIG. 6B is a side view illustrating a method of expanding a
laminate film according to an embodiment.
DESCRIPTION OF EMBODIMENTS
[0057] 1. Expandable Film
[0058] An expandable film of the present invention contains (A) a
1-butene-.alpha.-olefin copolymer and (B) propylenic elastomer
composition.
[0059] (A) 1-butene-.alpha.-olefin Copolymer
[0060] The 1-butene-.alpha.-olefin copolymer (A) contained in the
expandable film is a polymer containing 1-butene as the primary
component. The .alpha.-olefins in the 1-butene-.alpha.-olefin
copolymer (A) may be .alpha.-olefins having 2 to 10 carbon atoms
other than 1-butene. Examples of the .alpha.-olefins having 2 to 10
carbon atoms include ethylene, propylene, 1-pentene, 1-hexene,
1-heptene, 1-octene, 1-nonene, and 1-decene. Preferred are ethylene
and propylene. The .alpha.-olefins contained in the
1-butene-.alpha.-olefin copolymer (A) may be used alone or in
combination. The amount of 1-butene contained in the
1-butene-.alpha.-olefin copolymer (A) is preferably 80 mol % or
more, and more preferably 90 mol % or more. An amount less than 80
mol % fails to ensure sufficient expandability.
[0061] The 1-butene-.alpha.-olefin copolymer (A) may have any
density and has a density of 890 to 950 kg/m.sup.3 in a preferred
embodiment. A lower density leads to a decrease in tensile modulus
and thus insufficient expandability.
[0062] The film containing the 1-butene-.alpha.-olefin copolymer
(A) has a tensile strength of preferably 100 to 500 MPa and more
preferably 150 to 450 MPa at 23.degree. C. An excessively high
tensile strength makes expansion of the film difficult due to its
high hardness. An excessively low tensile strength leads to poor
handling performance due to excessive softness of the film.
[0063] The 1-butene-.alpha.-olefin copolymer (A) may have any melt
flow rate (MFR) which is determined at 230.degree. C. and a load of
2.16 kg in accordance with ASTM D1238, provided that the copolymer
can be readily compatible with the propylenic elastomer composition
(B) in an extruder. The MFR is in the range of preferably 1 to 20
g/10 min and more preferably 1 to 10 g/10 min since the copolymer
can be uniformly extruded with the propylenic elastomer composition
(B).
[0064] The 1-butene-.alpha.-olefin copolymer (A) can be prepared by
any known process, for example, copolymerization of 1-butene with
any .alpha.-olefin other than 1-butene in the presence of a
Ziegler-Natta or metallocene catalyst.
[0065] Propylenic Elastomer Composition (B)
[0066] The propylenic elastomer composition (B) contained in the
expandable film contains a propylene-.alpha.-olefin copolymer (b1)
as the primary component and preferably further contains
polypropylene (b2).
[0067] The propylene-.alpha.-olefin copolymer (b1) represents a
copolymer of propylene with an .alpha.-olefin other than propylene.
Preferred .alpha.-olefins for constituting the
propylene-.alpha.-olefin copolymer (b1) are .alpha.-olefins having
2 to 20 carbon atoms. Examples of the .alpha.-olefins having 2 to
20 carbon atoms include ethylene, 1-butene, 1-pentene, 1-hexene,
1-heptene, 1-octene, 1-nonene, and 1-decene. Preferred are ethylene
and 1-butene. The .alpha.-olefins for constituting the
propylene-.alpha.-olefin copolymer (b1) may be used alone or in
combination. The propylene-.alpha.-olefin copolymer (b1) is more
preferably a propylene/1-butene/ethylene copolymer.
[0068] The amount of propylene monomer units in the
propylene-.alpha.-olefin copolymer (b1) is preferably 50 mol % or
more, and more preferably 60 mol % or more in view of achieving
satisfactory rubber elasticity.
[0069] The propylene-.alpha.-olefin copolymer (b1) has rubber
elasticity at a treating temperature of the expandable film and
preferably has a glass transition temperature of 25.degree. C. or
less. A glass transition temperature above 25.degree. C. may cause
physical properties such as expandability of the shaped film to
readily vary depending on storage conditions.
[0070] Polypropylene (b2) is substantially a homopolymer of
propylene and may contain trace amounts of .alpha.-olefins other
than propylene; thus, polypropylene may be any one of so-called
homopolypropylene (hPP), random polypropylene (rPP), and block
propylene (bPP). The amount of .alpha.-olefin other than propylene
in the polypropylene (b2) is preferably 20 mol % or less and more
preferably 10 mol % or less. Such polypropylene (b2) will have
several advantageous effects such as suppression of blocking of the
propylene-.alpha.-olefin copolymer (b1) and improved film
formability.
[0071] The amount of polypropylene (b2) is preferably 1 to 70
weight parts, more preferably 5 to 70 weight parts, further
preferably 5 to 30 weight parts, and most preferably 5 to 20 weight
parts relative to 100 weight parts in total of the propylenic
elastomer composition (B). An amount of polypropylene (b2) below 1
part by weight may lead to blocking of the propylene-.alpha.-olefin
copolymer (b1), resulting in instable extrusion of the composition
during the film extrusion process in some cases. An amount of
polypropylene (b2) above 30 weight parts may lead to a small
expansion rate in some cases.
[0072] The film of the propylenic elastomer composition (B) has a
tensile modulus of preferably 8 to 500 MPa, more preferably 10 to
500 MPa, still more preferably 10 to 100 MPa, further preferably 10
to 50 MPa, and most preferably 10 to 45 MPa at 23.degree. C.
[0073] The propylenic elastomer composition (B) may have any melt
flow rate (MFR) provided that the propylenic elastomer composition
(B) can be readily compatible with the 1-butene-.alpha.-olefin
copolymer (A) in an extruder. The MFR, which is determined at
230.degree. C. and a load of 2.16 kg in accordance with ASTM D1238,
is in the range of preferably 1 to 20 g/10 min and more preferably
1 to 10 g/10 min since the composition can be extruded to have a
relatively uniform thickness.
[0074] The amount of the propylenic elastomer composition (B)
contained in the expandable film is in the range of preferably 30
to 70 weight parts, and more preferably 40 to 60 weight parts
relative to 100 weight parts in total of the components (A) and
(B).
[0075] The expandable film can be prepared through dry blending or
melt blending followed by extrusion of the 1-butene-.alpha.-olefin
copolymer (A) and the propylenic elastomer composition (B). The
resulting expandable film has a microdispersion structure
containing the 1-butene-.alpha.-olefin copolymer (A) having
relatively high crystallinity and high tensile modulus and the
propylenic elastomer composition (B) having relatively low
crystallinity and low tensile modulus.
[0076] FIG. 1A is an example of a sectional TEM image parallel to
the MD direction of the expandable film, while FIG. 1B is an
example of a sectional TEM image parallel to the TD direction of
the expandable film. As shown in FIGS. 1A and 1B, bright portions
(1-butene-.alpha.-olefin copolymer (A)) are observed, extending in
the direction parallel to the film surface in the TEM images.
[0077] Such a structure of microphase separation can be observed in
a form of "light-dark structure" in a section of a transmission
electronic microscopic (TEM) image of a thin section sample of the
expandable film. In the TEM image in FIG. 1, it is observed that,
for example, "bright portions" corresponding to
1-butene-.alpha.-olefin copolymer (A) and "dark portions"
corresponding to propylenic elastomer composition (B). Such a
structure of microphase separation is not formed in a system of
highly crystalline olefinic resin and lowly crystalline olefinic
resin disclosed in Patent Literature 5 (Japanese Patent No.
3340979), but can be formed by a specific combination of the
1-butene-.alpha.-olefin copolymer (A) and propylenic elastomer
composition (B) in the present invention.
[0078] The mechanism is not clear but is speculated as follows:
Stress applied to an expandable film having a structure of
microphase separation leads to elastic deformation of the
1-butene-.alpha.-olefin copolymer (A). This deformation
uniformalizes the stress applied to the 1-butene-.alpha.-olefin
copolymer (A) via the propylenic elastomer composition (B) in the
cross-section direction of the film before necking occurs. The
uniform deformation results in isotropic deformation of the
higher-order structure of the 1-butene-.alpha.-olefin copolymer (A)
in the overall expandable film. The elastically deformable range is
thus enlarged without occurrence of necking.
[0079] The expandable film can be observed as follows: The
expandable film is cut in the directions parallel to the MD and TD
directions into two 100 .mu.m thick samples, and the resulting
cross-sectional surfaces are observed with a transmission electron
microscope (TEM, H-7650 manufactured by Hitachi Ltd.) at a
magnification of 5,000 to 20,000.
[0080] The expandable film can have any thickness without
restriction. In the case where the expandable film of the present
invention is used as a dicing film for semiconductors, the
substrate layer preferably has a thickness of about 50 to about 200
.mu.m.
[0081] The expandable film of the present invention can be prepared
by blending components and then extruding the blend (extrusion
process). In the case where the expandable film contains
polypropylene (b2), it is preferred that a pre-blend (propylenic
elastomer composition (B)) of propylene-.alpha.-olefin copolymer
(hi) and polypropylene (b2) be blended with 1-butene-.alpha.-olefin
copolymer (A) and any other component and the blend is extruded
into the expandable film. Such pre-blending of polypropylene (b2)
and propylene-.alpha.-olefin copolymer (b1) can adjust the
compatibility between the 1-butene-.alpha.-olefin copolymer (A) and
the propylenic elastomer composition (B), facilitating formation of
phase separation structure.
[0082] The expandable film of the present invention exhibits
superior handling performance and expandability. The expandable
film of the present invention can therefore be used in various
applications requiring expandability, such as protective members
for optical devices and dicing films used for semiconductor
devices, and preferably dicing films for semiconductor devices.
[0083] 2. Dicing Film
[0084] The dicing film of the present invention includes a
substrate layer containing the expandable film described above, and
may further include an adhesive layer, an intermediate layer, and a
low-friction layer, if necessary.
[0085] Some semiconductor wafers to be diced have polyimide films,
aluminum electrodes, and scribe lines for dicing on their surfaces
and thus their surfaces have irregularities. In recent years,
wafers have been developed frequently which are provided with gold
bumps having large irregularities compared to standard LSIs and
solder ball bumps used for mount boards of high-frequency devices.
In such a circumference, a big challenge is to prevent damaging of
semiconductor wafers having such surface irregularities during
dicing.
[0086] A possible dicing process for wafers having large
irregularities involves bonding a dicing film onto a patterned
surface of the wafer and cutting the wafer from the other
non-patterned surface with a rotating blade. If the dicing film
used does no absorb irregularities, gaps are formed between the
adhesion surface and the patterned surface, and debris generated
during cutting may damage the patterned surface, resulting in
insufficient control of contamination.
[0087] In the case where the dicing film of the present invention
is used in such applications, the dicing film preferably include an
intermediate layer that can absorb surface irregularities of the
semiconductor wafer. The dicing film of the present invention
including an intermediate layer described later can come into close
contact with the surface irregularities of the semiconductor wafer,
preventing contamination of the patterned surface and damaging of
the semiconductor wafer during dicing.
[0088] If adhesion between a ring frame used for dicing and the
dicing film is insufficient, the dicing film may detached from the
ring frame during dicing. Thus, the dicing film of the present
invention preferably has high adhesion to the ring frame.
Accordingly, the dicing film of the present invention preferably
has an adhesive layer (described below) as an outermost layer to be
bonded to the ring frame.
[0089] (1) Adhesive Layer
[0090] The adhesive layer may be composed of any known adhesive.
Examples of the adhesive include adhesives of rubber adhesives,
acrylic adhesives, silicone adhesives, and thermoplastic elastomers
such as styrenic elastomers and olefinic elastomers. Alternatively,
the adhesive layer may be composed of radiation-curable adhesives
of which the adhesive force decreases by radiation rays or
heat-curable adhesives of which the adhesive force decreases by
heat. Examples of the radiation-curable adhesives include
UV-curable adhesives.
[0091] The acrylic adhesives may be homopolymers of acrylate esters
or copolymers of acrylate esters with comonomers. Examples of the
acrylate esters include ethyl acrylate, butyl acrylate, and
2-ethylhexyl acrylate. Examples of the comonomers for constituting
the acrylic copolymers include vinyl acetate, acrylonitrile,
acrylamide, styrene, methyl methacrylate, methyl acrylate,
methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl
methacrylate, hydroxypropyl methacrylate, (dimethylamino)ethyl
methacrylate, acrylamide, methylol acrylamide, glycidyl
methacrylate, and maleic anhydride.
[0092] Examples of the rubber adhesives include natural rubber,
synthetic isoprene rubbers, styrene-butadiene rubbers,
styrene/butadiene block copolymers, styrene/isoprene block
copolymers, butyl rubber, polyisobutylene, polybutadiene, polyvinyl
ethers, silicone rubbers, and chloroprene rubbers.
[0093] The rubber adhesives may further contain tackifier resins in
order to enhance its adhesiveness. Examples of the tackifier resins
include rosin resins and terpene resins. Preferred are terpene
resins, which are high compatibility with rubber adhesives.
Examples of the rosin resins include rosin, polymerized rosin,
hydrogenated rosin, and rosin esters. Examples of the terpene
resins include terpene resins, terpene phenolic resins,
aromatic-modified terpene resins, and rosin phenolic resins. The
amount of the tackifier resin is preferably in the range of 5 to
100 weight parts relative to 100 weight parts of the rubber
adhesive.
[0094] Examples of the thermoplastic elastomers include polystyrene
elastomers, polyolefin elastomers, polyurethane elastomers, and
polyester elastomers. Among them preferred are polystyrene
elastomers and polyolefin elastomers which can readily control
adhesiveness and flexibility.
[0095] Examples of the polystyrene elastomers include
styrene-isoprene-styrene block copolymers (SIS),
styrene-ethylene/butylene-styrene block copolymers (SEBS),
styrene-ethylene/propylene-styrene block copolymers (SEPS), other
styrene-diene block copolymers, and hydrogenated products (e.g.,
hydrogenated styrene-butadiene rubbers (HSBR)) thereof.
[0096] Examples of the polyolefin elastomers include block
copolymers consisting of crystalline polyolefin blocks and
amorphous co-monomer blocks. Specific examples include olefin
(crystalline)-ethylene-butylene-olefin (crystalline) block
copolymers, polypropylene-poly(ethylene oxide)-polypropylene block
copolymers, and polypropylene-polyolefin-polypropylene block
copolymers. Preferred polyolefin elastomers are polyethylene
elastomers.
[0097] The UV-curable adhesives and heat-curable adhesives contain
adhesive components such as acrylic adhesives, curable compounds
(having carbon-carbon double bonds), and photo- or
thermal-polymerization initiators.
[0098] The curable compounds include monomers, oligomers, and
polymers having carbon-carbon double bonds in their molecules and
can be cured by radical polymerization.
[0099] Examples of such curable compounds include esters of
(meth)acrylic acids with polyhydric alcohols such as
trimethylolpropane tri(meth)acrylate, pentaerythritol
tri(meth)acrylate, tetraethylene glycol di(meth)acrylate,
1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate,
and dipentaerythritol hexa(meth)acrylate; oligomers of the ester;
and isocyanurate or isocyanurate compounds such as 2-propenyl
di-3-butenylcyanurate,
2-hydroxyethylbis(2-acryloxyethyl)isocyanurate, and
tris(2-methacryloxyethyl)isocyanurate. In the case where the
adhesive is of a UV-curable polymer type having carbon-carbon
double bonds in its side chain(s), the curable compound is
unnecessary.
[0100] The amount of the curable compound is in the range of
preferably 5 to 900 weight parts and more preferably 20 to 200
weight parts relative to 100 weight parts of adhesive agent. A
smaller amount of curable compound leads to insufficient adhesive
force due to a low amount of cured component, whereas a larger
amount of curable compound leads to low storage stability due to
excess sensitivity to heat and light.
[0101] Any photopolymerization initiator can be used which can be
cleaved by UV irradiation to form radials. Examples of such
initiators include benzoin alkyl ethers such as benzoin methyl
ether, benzoin isopropyl ether, and benzoin isobutyl ether;
aromatic ketones such as benzyl, benzoin, benzophenone, and
.alpha.-hydroxycyclohexyl phenyl ketone; aromatic ketals such as
benzyl dimethyl ketal; polyvinyl benzophenone; and thioxanthones
such as chlorothioxanthone, dodecylthioxanthone,
dimethylthioxanthone, and diethylthioxanthone.
[0102] Thermal polymerization initiators may be organic peroxide
derivatives and azo polymerization initiators. Preferred are
organic peroxide derivatives, which do not generate nitrogen when
being heated. Examples of the thermal polymerization include ketone
peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl
peroxides, peroxyesters, and peroxycarbonates.
[0103] The adhesive agent may contain a cross-linking agent.
Examples of the adhesive agent include epoxy compounds such as
sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether,
pentaerythritol polyglycidyl ether, and diglycerol polyglycidyl
ether; aziridine compounds such as
tetramethylolmethane-tri-.beta.-aziridinyl propionate,
trimethylolpropane-tri-.beta.-aziridinyl propionate,
N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), and
N'-hexamethylene-1,6-bis(1-aziridinecarboxamide); isocyanate
compounds, such as tetramethylene diisocyanate, hexamethylene
diisocyanate, and polyisocyanates.
[0104] The adhesive layer preferably has an adhesive force in
accordance with JIS Z0237 of 0.1 to 10 N125 mm after the adhesive
layer is bonded onto a surface of a stainless steel-304-BA plate,
is allowed to stand for 60 minutes, and then is separated from the
stainless steel-304-BA. An adhesive force within such a range
achieves high adhesiveness to wafers and does not leave any
adhesive on the chips after the chips are separated from the
adhesive layer. The adhesive force of the adhesive layer can be
controlled by the amount of added cross-linking agent. It can be
controlled by the method, for example, disclosed in Japanese
Unexamined Patent Application Publication No. 2004-115591.
[0105] The adhesive layer may have any thickness within a range not
precluding expansion of the substrate layer. It is preferred that
the thickness range generally from 1 to 50 .mu.m and preferably 1
to 25
[0106] (2) Intermediate Layer
[0107] The intermediate layer can absorb the irregularities of the
semiconductor wafer. As described later, the intermediate layer may
be provided, for example, between the substrate layer and the
adhesive layer, or may function as the adhesive layer.
[0108] The intermediate layer preferably has a tensile modulus
E(25) at 25.degree. C. and a tensile modulus E(60) at 60.degree. C.
satisfying the relation E(60)/E(25)<0.1, more preferably
E(60)/E(25)<0.08, and most preferably E(60)/E(25)<0.05. A
ratio of the tensile moduli at 60.degree. C. to 25.degree. C.
satisfying the range described above causes the intermediate layer
to have thermal fusibility and to plastically deform. In detail,
the intermediate layer can come into close contact with the uneven
patterned surface of the semiconductor wafer when the sheet is
bonded at elevated temperature and can maintain (fix) the state of
the close contact with the uneven patterned surface at normal
temperature after the sheet is bonded.
[0109] The intermediate layer has a tensile modulus E (25) at
25.degree. C. of preferably 1 MPa to 10 MPa and more preferably 2
MPa to 9 MPa. A tensile modulus E(25) within such a range allows
the intermediate layer to maintain the shape at normal temperature
after the sheet is bonded and to maintain the close contact during
processing. The intermediate layer has a tensile modulus E (60) at
60.degree. C. of preferably 0.005 MPa to 1.0 MPa and more
preferably 0.01 MPa to 0.5 MPa. A tensile modulus E(60) within such
a range allows the intermediate layer to have flowability when the
sheet is bonded at elevated temperature and thus well absorbs
irregularities.
[0110] The tensile modulus of the resin can be measured as follows:
1) A sample film of an initial length of 140 mm, a width of 10 mm,
a thickness of 75 to 100 .mu.m is prepared as a testing sample; 2)
The film is subjected to tensile test at a measurement temperature
of 25.degree. C. and a tensile rate of 50 mm/min with a
chuck-to-chuck distance of 100 mm, to determine a difference (mm)
in elongation of the sample; and 3) A tangential line is drawn at
the initial incremental portion of the resulting S-S curve
(stress-strain curve), and the tensile modulus is determined by the
slope of the tangential line divided by the cross-sectional area of
the sample film.
[0111] The intermediate layer has a density in the range of
preferably 800 to 890 kg/m.sup.3, more preferably 830 to 890
kg/m.sup.3, and most preferably 850 to 890 kg/m.sup.3. A density of
the intermediate layer less than 800 kg/m.sup.3 leads to
significantly low modulus that causes low shape stability whereas a
density higher than 890 kg/m.sup.3 leads to significantly high
modulus that causes poor absorption of surface irregularities.
[0112] The intermediate layer may be composed of any resin that
satisfies the tensile modulus described above, and preferably
composed of an olefinic copolymer. Preferred .alpha.-olefinic
copolymers are same as those of main building blocks consisting of
.alpha.-olefin having 2 to 12 carbon atoms.
[0113] Examples of the .alpha.-olefin having 2 to 12 carbon atoms
include ethylene, propylene, 1-butene, 1-pentene,
3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene,
3-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, and
1-dodecene.
[0114] Among them preferred are ethylene-.alpha.-olefin copolymers,
such as ethylene-propylene copolymers, ethylene-1-butene
copolymers, and ternary copolymers consisting of ethylene,
propylene, and an .alpha.-olefin having 4 to 12 carbon atoms; and
ternary copolymers of consisting of propylene, 1-butene, and an
.alpha.-olefin having 5 to 12 carbon atoms in view of superior
absorption of surface irregularities. Ethylene-propylene copolymers
are more preferred since propylene has high thermal fusibility
among polyolefinic copolymers. Commercially available
.alpha.-olefinic copolymers include TAFMER (registered trademark)
commercially available from Mitsui Chemicals, Inc.
[0115] The tensile modulus of the intermediate layer can be
controlled by the kinds and proportion of monomers constituting the
olefinic copolymer and the degree of modification thereof. For
example, the tensile modulus at 60.degree. C. of the olefinic
copolymer can be decreased, for example, by increasing the
proportion of propylene in the copolymer or by modifying the
copolymer with carboxylic acid.
[0116] The intermediate layer may contain any other resin or
additive in an amount that does not impair adhesion/separation
characteristics to/from semiconductor wafers. Examples of such
additives include ultraviolet absorbers, antioxidants, thermal
stabilizers, slipping agents, softening agents, and tackifiers.
[0117] The thickness of the intermediate layer is preferably larger
than the height of irregularities on one surface of a semiconductor
wafer (surface to which the dicing film is bonded) and can be any
value as long as it can absorb irregularities (including solder
bumps) on the patterned surface of the wafer. For example, the
thickness of the intermediate layer may be 100 to 300 .mu.m for
irregularities of about 100 .mu.m in height. More specifically, the
thickness of the intermediate layer is preferably one to three
times and more preferably one to two times of the height of the
irregularities on the wafer surface.
[0118] (3) Low-Friction Layer
[0119] The dicing film of the present invention may further include
a low-friction layer on an opposite side of the dicing film to the
adhesive layer, if necessary. In the case where the dicing film is
used as a dicing film for semiconductor as described later, the
dicing film is expanded by lifting up a stage of an expander from
the lower surface in the center of the dicing film, with a ring
frame fixed at the periphery of the dicing film (refer to FIG. 6
which will be explained later). If the side, in contact with the
stage, of the dicing film has large friction, the film cannot
readily slide on the stage and thus cannot be expanded at the
portion in contact with the stage. A reduction in friction of the
side, in contact with the stage, of the dicing film, more
specifically, provision of providing a low-friction layer
facilitates slide of the stage of the expander and thus allow the
entire surface of the dicing film to be uniformly expanded.
[0120] Such a low-friction layer is composed of a resin, such as
polyethylene or an ethylenic ionomer resin. The exposed surface of
the low-friction layer may be coated with or contain a slipping
agent in order to further enhance slippage. Examples of the
slipping agent include erukamide, oleamide, silicone oil, and
masterbatches containing high concentrations of these slipping
agents (slipping agent masterbatch).
[0121] (4) Layer Configuration of Dicing Film
[0122] The dicing film of the present invention may have any layer
configuration without restriction; the dicing film may have a
double-layer configuration consisting of a substrate layer and an
adhesive layer or consisting of a substrate layer and an
intermediate layer, or a triple-layer configuration consisting of a
substrate layer, an intermediate layer, and an adhesive layer
laminated in this order. Alternatively, the dicing film may be a
laminate of four or more layers including another or other layers
such as a low-friction layer in addition to the adhesive layer and
the intermediate layer. In the case of a laminate dicing film
having an adhesive layer and a low-friction layer in the present
invention, preferably the adhesive layer is disposed on one side of
the substrate layer while the low-friction layer on the other side.
Any other layer may be disposed between the substrate layer and the
adhesive layer, between the substrate layer and the intermediate
layer, between the intermediate layer and the adhesive layer, or
between the substrate layer and the low-friction layer, provided
that the advantageous effects of the present invention are not
impaired. The substrate layer, intermediate layer, and adhesive
layer may each have a multilayer configuration. If multiple
substrate layers are disposed, any other layer may be provided
between the substrate layers.
[0123] FIG. 2 is a schematic cross-sectional view of a dicing film
according to an embodiment of the present invention. As shown in
FIG. 2, the dicing film includes an expandable substrate layer 12,
an adhesive layer 14 disposed on one side of the substrate layer 12
and to be bonded to a wafer, and a low-friction layer 16 disposed
on the other side of the substrate layer 12, remote from the
adhesive layer 14. The dicing film 10 having such a configuration
including the substrate layer 12 has high expandability.
[0124] FIG. 3 is a schematic cross-sectional view of a dicing film
according to another embodiment of the present invention. As shown
in FIG. 3, the dicing film includes an expandable substrate layer
12, an intermediate layer 13 disposed on one side of the substrate
layer 12 and absorbs irregularities on a wafer, an adhesive layer
14 to be bonded to the wafer, and a low-friction layer 16 disposed
on the other side of the substrate layer 12, remote from the
adhesive layer 14. The dicing film 10 having such a configuration
including the substrate layer 12 has high expandability. The
intermediate layer 13 can come into close contact with large
irregularities on the wafer when the dicing film is bonded to the
semiconductor wafer having the irregularities, resulting in
preventing contamination of the wafer surface and damaging of the
semiconductor chips during dicing.
[0125] A dicing film not including an intermediate layer of the
present invention has a total thickness in the range of preferably
50 to 200 .mu.m and more preferably 70 to 150 .mu.m. A dicing film
including an intermediate layer between a substrate layer and an
adhesive layer of the present invention has a total thickness in
the range of preferably 60 to 700 .mu.m and more preferably 80 to
500 .mu.m.
[0126] The dicing film of the present invention preferably has a
tensile modulus at 23.degree. C. of 70 MPa or more. A tensile
modulus less than 70 MPa leads to low handling performance due to
wrinkling of the dicing film when the dicing film is bonded to a
wafer.
[0127] The dicing film of the present invention may further include
an optional separator on the surface of the adhesive layer to
protect the surface of the adhesive layer. The separator may be
composed of paper, or a synthetic resin such as polyethylene,
polypropylene, or polyethylene terephthalate. The separator
typically has a thickness of about 10 to about 200 .mu.m and
preferably about 25 to about 100 .mu.m.
[0128] Since the dicing film of the present invention does not
contain polyvinyl chloride (PVC) or any other chlorine components,
chloride ions creating environmental damage do not occur. Since the
dicing film of the present invention contains no plasticizer, the
contamination of wafers can be reduced. In addition, the dicing
film of the present invention having high expandability barely
undergoes necking.
[0129] 3. Method of Manufacturing Dicing Film
[0130] The dicing film of the present invention can be produced by
any process. In the case where the dicing film of the present
invention is a laminate film including an adhesive layer and a
low-friction layer in addition to a substrate layer, the dicing
film may be produced through 1) lamination by coextrusion of melt
resins constituting individual layers (coextrusion process); 2)
lamination of melt resins constituting individual layers on a
substrate layer (extrusion lamination process); 3) lamination of
films constituting individual layers by thermal compression bonding
or with an adhesive (lamination process); or 4) application
(coating) of a resin composition constituting an adhesive layer on
a substrate layer or on a resin laminate consisting of a substrate
layer and an intermediate layer.
[0131] Two or more resins can be blended by any process without
restriction before extrusion or coextrusion, for example, by dry
blend with any of a various types of mixers such as Henschel mixer
and tumbler mixer (dry blend process); or by melt blend with a
uniaxial extruder or biaxial extruder (melt blend process).
Preferred is melt blend with a biaxial extruder.
[0132] Any melt blend temperature may be employed suitable for melt
blend of resins constituting individual layers. The melt
temperature of resin constituting the substrate layer is, for
example, in the range of 180 to 260.degree. C. Any extrusion
process can be employed, for example, inflation extrusion or T-die
extrusion.
[0133] In the case where a dicing film is produced by coextrusion
of a resin composition constituting the substrate layer and a resin
composition constituting the adhesive layer or by extrusion
lamination of a resin composition constituting the adhesive layer
on the substrate layer, it is preferred that the MFR of the
substrate layer at 230.degree. C. and the MFR of the adhesive layer
at 230.degree. C. determined in accordance with ASTM D1238 be each
in the range of 1 to 20 g/10 min. These layers having such MFR can
be shaped to have a uniform thickness.
[0134] Similarly, in the case where a dicing film is produced by
coextrusion of a resin composition constituting the substrate layer
and a resin composition constituting the intermediate layer or by
extrusion lamination of a resin composition constituting the
intermediate layer on the substrate layer, it is preferred that the
MFR of the substrate layer at 230.degree. C. and the MFR of the
intermediate layer at 230.degree. C. determined in accordance with
ASTM D1238 are each in the range of 1 to 20 g/10 min. These layers
having such MFR can be shaped to have a uniform thickness.
[0135] Similarly, in the case where a dicing film is produced by
coextrusion of a resin composition constituting the substrate
layer, a resin composition constituting the intermediate layer, and
a resin composition constituting the adhesive layer or by extrusion
lamination of a resin composition constituting the intermediate
layer and a resin composition constituting the adhesive layer on
the substrate layer, it is preferred that the MFR of the substrate
layer at 230.degree. C., the MFR of the intermediate layer at
230.degree. C., and the MFR of the adhesive layer at 230.degree. C.
determined in accordance with ASTM D1238 are each in the range of 1
to 20 g/10 min. These layers having such MFR can be shaped to have
a uniform thickness.
[0136] In the case where the adhesive agent constituting the
adhesive layer is a radiation-curable adhesive agent, the adhesive
agent is preferably applied onto a substrate layer directly or onto
a resin laminate of a substrate layer and an intermediate layer
followed by drying (coating process described above). The resin
laminate of the substrate layer and the intermediate layer can be
produced by coextrusion of a resin composition constituting the
substrate layer and a resin composition constituting the
intermediate layer or by extrusion lamination of a resin
composition constituting the intermediate layer onto the substrate
layer.
[0137] 4. Method of Manufacturing Semiconductor Device
[0138] The method of manufacturing a semiconductor device using a
dicing film of the present invention includes the steps of: 1)
bonding the dicing film of the present invention to the rear
surface of a semiconductor wafer with an adhesive layer
therebetween; 2) dicing the semiconductor wafer; 3) expanding the
dicing film and picking up the diced semiconductor wafer pieces
(semiconductor chips); and 4) mounting the semiconductor chips to a
die pad or the like (not shown) of a semiconductor device by
bonding. The dicing film of the present invention has been
described above.
[0139] FIGS. 4A to 4E illustrate an example of a method of
manufacturing a semiconductor device using a dicing film 30
including a substrate layer 32 provided with an adhesive layer 34
on one surface and a low-friction layer 36 on the other surface
thereof. As shown in FIG. 4A, a wafer 22 is provided. As shown in
FIG. 4B, the wafer 22 is then bonded to a dicing film 30 of the
present invention (step 1 described above). The dicing film 30 has
a larger diameter than the wafer 22 such that its periphery can be
fixed with a ring frame 26. The periphery of the dicing film 30 is
then fixed with the ring frame 26.
[0140] As shown in FIG. 4C, the wafer 22 is diced (cut) into
semiconductor chip 22A (step 2 described above). The cut depth can
be set so as to reach the interface between the substrate layer 32
and the adhesive layer 34 of the dicing film 30. Cutting may be
carried out by any means, for example, with a dicing saw or by
laser.
[0141] As shown in FIG. 4D, the dicing film 30 is expanded (step 3
described above). Examples of expansion of the dicing film 30
include lifting up a stage of an expander under the dicing film 30
to expand a portion, in contact with the stage, of the dicing film
30 and stretching (extending) the dicing film 30 in a direction
parallel to the film plane.
[0142] As shown in FIG. 4E, spaces between semiconductor chips 22A
produced by dicing can thereby be expanded. Furthermore, expansion
of the dicing film 30 generates shear stress between the adhesive
layer 34 of the dicing film 30 and the wafer 22. This decreases the
adhesive force between the wafer 22 and the adhesive layer 34, and
thus facilitates pickup of the semiconductor chips 22A. Through
pickup of the semiconductor chips 22A, the semiconductor chips 22A
can be separated from the adhesive layer 34 of the dicing film
30.
[0143] FIGS. 5A to 5E illustrate an example of a method of
manufacturing a semiconductor device using a dicing film 50
including a substrate layer 52 provided with an intermediate layer
53 and the adhesive layer 54 provided in this order on one side and
a low-friction layer 56 on the other side thereof.
[0144] As shown in FIG. 5A, a wafer 42 having surface
irregularities such as circuits and the dicing film 50 are
provided. The wafer 42 provided with circuits may have a circuit
protecting layer to protect the circuits. The circuit protecting
layer may be composed of insulating resin, for example, polyimide
or polybenzoxazole.
[0145] As shown in FIG. 5B, the uneven surface of the wafer 42 is
bonded to the dicing film 50 of the present invention under heat
(step 1 described above). Bonding may be performed at a temperature
of 40.degree. C. to 80.degree. C. and a pressure of 0.3 to 0.5 MPa.
At a temperature of less than 40.degree. C., the intermediate layer
53 inevitably has high modulus and thus less absorbs the
irregularities. A bonding temperature exceeding 80.degree. C. is
undesirable as a process temperature. Bonding of the dicing film 50
may be performed with a known tape bonding machine.
[0146] After bonding of the wafer 42, the dicing film 50 may be
cooled. Cooling of the dicing film 50 to a temperature below the
bonding temperature causes the modulus of the intermediate layer 53
to increase, resulting in satisfactorily close contact between the
intermediate layer 53 and the uneven surface of the wafer 42.
[0147] The dicing film 50 has a larger diameter than the wafer 42
such that its periphery can be fixed with a ring frame 46. The
periphery of the dicing film 50 is then fixed with the ring frame
46.
[0148] As shown in FIG. 5C, the wafer 42 is diced (cut) into
semiconductor chips 42A (step 2 described above). The cut depth can
be set so as to reach the interface between the substrate layer 52
and the intermediate layer 53 of the dicing film 50. Cutting may be
carried out by any means, for example, with a dicing saw or by
laser.
[0149] As shown in FIG. 5D, the dicing film 50 is expanded (step 3
described above). Examples of expansion of the dicing film 50
include lifting up a stage of an expander under the dicing film 50
to expand a portion, in contact with the stage, of the dicing film
50, and stretching (extending) the dicing film 50 in a direction
parallel to the film plane.
[0150] As shown in FIG. 5E, spaces between semiconductor chips 42A
produced by dicing can thereby be expanded. Furthermore, expansion
of the dicing film 50 generates shear stress between the adhesive
layer 54 of the dicing film 50 and the wafer 42. This decreases the
adhesive force between the wafer 42 and the adhesive layer 54, and
thus facilitates pickup of the semiconductor chips 42A. Through
pickup of the semiconductor chips 42A, the semiconductor chips 42A
can be separated from the adhesive layer 54 of the dicing film
50.
EXAMPLES
[0151] (1) 1-Butene-.alpha.-olefin Copolymer (A)
[0152] 1-Butene-.alpha.-olefin copolymer (A1) (trade name: Tafmer
BL4000, available from Mitsui Chemicals, Inc.),
1-butene-.alpha.-olefin copolymer (A2) (trade name: Tafmer BL3450,
available from Mitsui Chemicals, Inc.), and 1-butene-.alpha.-olefin
copolymer (A3) (trade name: Tafmer BL2481, available from Mitsui
Chemicals, Inc.) shown in Table 1 were used as
1-butene-.alpha.-olefin copolymers (A) contained in a substrate
layer.
[0153] The density, tensile modulus, and MFR of the
1-butene-.alpha.-olefin copolymers (A1) to (A3) were determined as
follows: The results are shown in Table 1.
[0154] 1) Measurement of Density
[0155] The density was determined by a density gradient tube method
disclosed in Japanese Unexamined Patent Application Publication No.
2001-33372. Specifically, a produced 1-butene-.alpha.-olefin
copolymer sample was melted with a melt indexer to form a strand.
After the strand is annealed, it was cut into a proper size which
was then put into a density gradient tube.
[0156] The density gradient tube consisted of a glass cylinder that
was filled with liquid having a continuous density gradient. The
density of the solid sample of the put 1-butene-.alpha.-olefin
copolymer was determined from an equilibrium position at which the
sample got still in the liquid. The glass cylinder was filled with
a mixed solution of ethanol and water in accordance with Table 2 in
JIS K7112.
[0157] 2) Measurement of Tensile Modulus
[0158] A film composed of 1-butene-.alpha.-olefin copolymer (A) was
prepared. The tensile modulus of the film was determined in
accordance with ASTM D638. Specifically, i) a 100 .mu.m thick film
was cut into a strip specimen having a width (TD direction) of 10
mm and a length (MD direction) of 100 mm; and ii) the tensile
modulus of the specimen was determined with a tensilometer at a
distance between chucks of 50 mm and a tensile rate of 300 mm/min
in accordance with JIS K7161. The tensile modulus was measured at a
temperature of 23.degree. C. and a relative humidity of 55%.
[0159] 3) Measurement of MFR
[0160] The MFR of the 1-butene-.alpha.-olefin copolymer (A) was
measured at a temperature of 190.degree. C. or 230.degree. C. and a
load of 2.16 kg in accordance with ASTM D1238.
TABLE-US-00001 TABLE 1 A1 A2 A3 Copolymer Trade name Tafmer Tafmer
Tafmer BL4000 BL3450 BL2481 Properties Density (kg/m.sup.3) 915 900
900 Tensile modulus (MPa) 430 200 180 MFR(190.degree. C.) (g/10
min) 1.8 4.0 4.0 MFR(230.degree. C.) (g/10 min) 4.8 10 8.0
[0161] (2) Propylenic Elastomer Composition (B)
Synthesis of propylene-.alpha.-olefin Copolymer (b1)
Synthesis Example 1
[0162] After 833 ml of dry hexane, 100 g of 1-butene, and 1.0 mmol
of triisobutylaluminum at normal temperature were fed into a 2000
ml polymerization vessel thoroughly purged with nitrogen, the
polymerization vessel was heated to 40.degree. C. and then was
pressurized with propylene into 0.76 MPa. After the polymerization
vessel was pressurized with ethylene into 0.8 MPa, a toluene
solution containing 0.001 mmol of dimethylmethylene
(3-tert-butyl-5-methylcyclopentadienyl)fluorenylzirconium
dichloride and 0.3 mmol of methylaluminoxane (available from Tosoh
Finechem Corporation) on the basis of aluminum was placed into the
polymerization vessel. Polymerization was carried out for 20
minutes at an internal temperature of 40.degree. C. while the
internal pressure was maintained at 0.8 MPa with ethylene, and then
20 ml of methanol was added to quench the reaction. After releasing
the pressure, the polymerization solution was poured into 2 L of
methanol to precipitate the polymer, which was then dried for 12
hours at 130.degree. C. under vacuum to yield 36.4 g of
propylene-.alpha.-olefin copolymer (b1-1).
Synthesis Examples 2 to 4
[0163] Propylene-.alpha.-olefin copolymers (b1-2) to (b1-4) were
prepared as in Synthesis Example 1 except that the proportion of
propylene, ethylene, and 1-butene was changed as shown in Table
2.
[0164] The compositions of propylene-.alpha.-olefin copolymers
(b1-1) to (b1-4) prepared in Synthesis Examples 1 to 4 are
summarized in Table 2. The results are shown in Table 2.
TABLE-US-00002 TABLE 2 Synthesis Synthesis Synthesis Synthesis
Example 1 Example 2 Example 3 Example 4 (b1-1) (b1-2) (b1-3) (b1-4)
Composition Propylene 67 70 60 75 .alpha.-olefin Ethylene 14 10 16
18 1-Butene 19 20 24 7
Preparation of propylenic elastomer Composition (B)
Synthesis Example 5
[0165] 80 weight parts of propylene-.alpha.-olefin copolymer (b1-2)
prepared in Synthesis Example 2 and 20 weight parts of
homopolypropylene (b2) were kneaded with a biaxial extruder at
200.degree. C. to prepare a propylenic elastomer (B1).
Synthesis Example 6
[0166] A propylenic elastomer composition (B2) was prepared as in
Synthesis Example 5, except that 85 weight parts of
propylene-.alpha.-olefin copolymer (b1-3) prepared in Synthesis
Example 3 and 15 weight parts of polypropylene (b2) were
kneaded.
Synthesis Example 7
[0167] A propylenic elastomer composition (B3) was prepared as in
Synthesis Example 5, except that 90 weight parts of
propylene-.alpha.-olefin copolymer (b1-4) prepared in Synthesis
Example 4 and 10 weight parts of polypropylene (b2) were
kneaded.
Synthesis Example 8
[0168] A propylenic elastomer composition (B4) was prepared as in
Synthesis Example 5, except that 80 weight parts of
propylene-.alpha.-olefin copolymer (b1-1) prepared in Synthesis
Example 1 and 20 weight parts of polypropylene (b2) were
blended.
Synthesis Example 9
[0169] 70 weight parts of propylene-.alpha.-olefin copolymer (b1-2)
prepared in Synthesis Example 2 and 30 weight parts of
homopolypropylene (b2) were kneaded with a biaxial extruder at
200.degree. C. to prepare a propylenic elastomer (B5).
Synthesis Example 10
[0170] 60 weight parts of propylene-.alpha.-olefin copolymer (b1-2)
prepared in Synthesis Example 2 and 40 weight parts of
homopolypropylene (b2) were kneaded with a biaxial extruder at
200.degree. C. to prepare a propylenic elastomer (B6).
Synthesis Example 11
[0171] 50 weight parts of propylene-.alpha.-olefin copolymer (b1-2)
prepared in Synthesis Example 2 and 50 weight parts of
homopolypropylene (b2) were kneaded with a biaxial extruder at
200.degree. C. to prepare a propylenic elastomer (B7).
Synthesis Example 12
[0172] 30 weight parts of propylene-.alpha.-olefin copolymer (b1-2)
prepared in Synthesis Example 2 and 70 weight parts of
homopolypropylene (b2) were kneaded with a biaxial extruder at
200.degree. C. to prepare a propylenic elastomer (B8).
Synthesis Example 13
[0173] 20 weight parts of propylene-.alpha.-olefin copolymer (b1-2)
prepared in Synthesis Example 2 and 80 weight parts of
homopolypropylene (b2) were kneaded with a biaxial extruder at
200.degree. C. to prepare a propylenic elastomer (39).
[0174] The density, tensile modulus, and MFR of the resulting
propylenic elastomer compositions (B1) to (B9) were determined in
the manners described above. The results are shown in Table 3.
TABLE-US-00003 TABLE 3 Synthe- Synthe- Synthe- Synthe- Synthe-
Synthe- Synthe- Synthe- Synthe- sis Ex- sis Ex- sis Ex- sis Ex- sis
Ex- sis Ex- sis Ex- sis Ex- sis Ex- ample ample ample ample ample
ample ample ample ample 5 (B1) 6 (B2) 7 (B3) 8 (B4) 9 (B5) 10 (B6)
11 (B7) 12 (B8) 13 (B9) Composition Propylene- Type (b1-2) (b1-3)
(b1-4) (b1-1) (b1-2) (b1-2) (b1-2) (b1-2) (b1-2) .alpha.-olefin
Content 80 85 90 80 70 60 50 30 20 copolymer (b1) (weight parts)
Polypropylene Type (b2) (b2) (b2) (b2) (b2) (b2) (b2) (b2) (b2)
(b2) Content 20 15 10 20 30 40 50 70 80 (weight parts) Physical
Density (kg/m.sup.3) 868 866 868 867 866 868 867 867 867 properties
Tensile modulus (MPa) 42 12 25 16 60 90 160 420 700 MFR(230.degree.
C.) (g/10 min) 4 6 6 7 6 6 7 7 7
Example 1
Formation of Film
[0175] A 60/40 mixture on the mass basis of the
1-butene-.alpha.-olefin copolymer (A1) and propylenic elastomer
composition (B1) described above were prepared as raw materials for
a substrate layer. A linear low-density polyethylene, trade name:
Evolue SP2040 (available from Prime Polymer Co., Ltd., Vicat
softening point: 101.degree. C.) was provided as a raw material for
a low-friction layer. NOTIO PN3560 (trade name, available from
Mitsui Chemicals, Inc., MFR: 4 g/10 min at 230.degree. C. in
accordance with ASTM D1238) was provided as a raw material for an
adhesive layer.
[0176] Formation of Laminate Film
[0177] The raw materials for the substrate layer, low-friction
layer, and adhesive layer were put into respective extruders
provided with full-flight screws to be melt-kneaded. The melt
materials for the substrate layer, low-friction layer, and adhesive
layer were coextruded at an extrusion temperature of 230.degree. C.
from a multilayer die into a laminate film having a triple-layer
structure consisting of a low-friction layer, a substrate layer,
and an adhesive layer in this order. After a separator (Mitsui
Chemicals Tohcello Inc., trade name SP-PET) is further laminated on
the adhesive layer of the resulting laminate film, the film was
slit into a predetermined width which was rolled up.
Examples 2 to 3
[0178] Laminate films were prepared as in Example 1 except that the
proportion of the 1-butene-.alpha.-olefin copolymer (A1) and the
propylenic elastomer composition (B1) in the substrate layer was
changed as shown in Table 4.
Example 4
[0179] A laminate film was prepared as in Example 1 except that the
propylenic elastomer composition (B1) was replaced with a
propylenic elastomer composition (B2) in the substrate layer.
Examples 5 to 6
[0180] Laminate films were prepared as in Example 1 except that the
proportion of the 1-butene-.alpha.-olefin copolymer (A1) and the
propylenic elastomer composition (B2) in the substrate layer was
changed as shown in Table 4.
Example 7
[0181] A laminate film was prepared as in Example 1 except that the
proportion of the 1-butene-.alpha.-olefin copolymer (A1) and the
propylene-.alpha.-olefin copolymer (b1-4) in the substrate layer
was changed as shown in Table 5.
Example 8
[0182] A laminate film was prepared as in Example 1 except that the
raw material, NOTIO PN3560, for the adhesive layer is replaced with
a linear low-density polyethylene, Evolue SP2040 (trade name,
available from Prime Polymer Co., Ltd.).
Example 9
[0183] A laminate film was prepared as in Example 4 except that the
raw material, NOTIO PN3560, for the adhesive layer is replaced with
a linear low-density polyethylene, Evolue SP2040 (trade name,
available from Prime Polymer Co., Ltd.).
Example 10
[0184] A double-layer laminate film consisting of a substrate layer
and an adhesive layer was prepared as in Example 1 except that the
linear low-density polyethylene, Evolue SP 2040 (available from
Prime Polymer Co., Ltd.) for the low-friction layer is replaced
with the same material for the substrate layer.
Example 11
[0185] A laminate film having a double layer structure was prepared
as in Example 10 except that the raw material, NOTIO PN3560, for
the adhesive layer is replaced with NOTIO PN2060 (registered trade
mark, available from Mitsui Chemicals, Inc., MFR: 7 g/10 min at
230.degree. C. in accordance with ASTM D1238).
Example 12
[0186] A laminate film having a double layer structure was prepared
as in Example 10 except that the raw material, NOTIO PN3560, for
the adhesive layer is replaced with a hydrogenated
styrene-butadiene rubber (HSBR), DYNARON DR1322P (registered trade
mark, available from JSR Corporation).
Example 13
Preparation of UV-Curable Adhesive Coating Solution for Forming
UV-Curable Adhesive Layer
[0187] Ethyl acrylate (48 weight parts), 2-ethylhexyl acrylate (27
weight parts), methyl acrylate (20 weight parts), glycidyl
methacrylate (5 weight parts), and benzoyl peroxide (0.5 part by
weight) as a polymerization initiator were mixed. The mixture was
added dropwise with stirring into a nitrogen-purged flask charged
with toluene (65 weight parts) and ethyl acetate (50 weight parts)
at 80.degree. C. over 5 hours, and was further stirred for 5 hours
to complete the reaction. After the reaction, the solution was
cooled. Xylene (25 weight parts), acrylic acid (2.5 weight parts),
and tetradecylbenzylammonium chloride (1.5 weight parts) were
added, and the mixture was reacted at 80.degree. C. for 10 hours
while air was blew to yield a solution of an acrylic ester
copolymer having photopolymerizable carbon-carbon double bonds.
[0188] To the solution, 7 weight parts of benzoin as a
photoinitiator, 2 weight parts of an isocyanate cross-linking
agent, OLESTER P49-75S (trade name, available from Mitsui
Chemicals, Inc.), 15 weight parts of dipentaerythritol
hexaacrylate, AronixbM-400 (trade name, available from Toagosei Co.
Ltd.) as a low-molecular weight compound having two or more
photopolymerizable carbon-carbon double bonds per molecule were
added relative to 100 weight parts of the copolymer (solid
component) to yield a UV-curable adhesive coating solution.
[0189] Lamination of UV Adhesive Layer
[0190] The UV-curable adhesive coating solution was applied onto a
release-treated (silicone-treated) side of a 38 .mu.m thick PET
releasing film (available from TOHCELLO Co., Ltd., trade name
SP-PET) with a comma coater, and was dried at 120.degree. C. for 4
minutes to yield a UV-curable adhesive layer having a thickness of
30 .mu.m. A substrate film which was the same as that used in
Example 10 but had a corona-treated side was prepared. The
UV-curable adhesive layer formed on the PET film and the
corona-treated side of the substrate film were press-bonded with a
dry laminator to transfer the UV-curable adhesive layer onto the
corona-treated side of the substrate film to yield a laminate
film.
Example 14
[0191] A laminate film was prepared as in Example 1 except that the
raw material for the low-friction layer, linear low-density
polyethylene Evolue SP2040 (available from Prime Polymer Co., Ltd.)
was replaced with an ethylene-methacrylic acid copolymer NUCREL
AN4213C (trade name, available from DUPONT-MITSUI POLYCHEMICALS
CO., LTD, MFR: 10 g/10 min at 190.degree. C. in accordance with JIS
K7210 1999).
Example 15
[0192] A laminate film was prepared as in Example 1 except that the
raw material for the low-friction layer, linear low-density
polyethylene Evolue SP2040 (available from Prime Polymer Co., Ltd.)
was replaced with an ethylene-methacrylic acid copolymer NUCREL
N1108C (trade name, available from DUPONT-MITSUI POLYCHEMICALS CO.,
LTD, MFR: 8 g/10 min at 190.degree. C. in accordance with JIS K7210
1999).
Example 16
[0193] A laminate film was prepared as in Example 1 except that
both the raw material for the low-friction layer, linear
low-density polyethylene Evolue SP2040 (available from Prime
Polymer Co., Ltd.) and the raw material for the adhesive layer,
NOTIO PN3560 were replaced with an ethylene-methacrylic acid
copolymer NUCREL AN4213C (trade name, available from DUPONT-MITSUI
POLYCHEMICALS CO., LTD, MFR: 10 g/10 min at 190.degree. C. in
accordance with JIS K7210 1999).
Example 17
[0194] A laminate film was prepared as in example 10 except that
the propylenic elastomer composition (B1) in the substrate layer is
replaced with a propylenic elastomer composition (B3).
Example 18
[0195] A laminate film was prepared as in example 10 except that
the propylenic elastomer composition (B1) in the substrate layer is
replaced with a propylenic elastomer composition (B4).
Comparative Example 1
[0196] A laminate film was prepared as in example 1 except that
only a 1-butene-.alpha.-olefin copolymer (A1) was used as a raw
material for the substrate layer.
Comparative Example 2
[0197] A laminate film was prepared as in example 1 except that
only a 1-butene-.alpha.-olefin copolymer (A2) was used as a raw
material for the substrate layer.
Comparative Example 3
[0198] A laminate film was prepared as in example 1 except that
only a 1-butene-.alpha.-olefin copolymer (A3) was used as a raw
material for the substrate layer.
Comparative Example 4
[0199] A laminate film was prepared as in example 1 except that the
proportion of the 1-butene-.alpha.-olefin copolymer (A1) to the
propylenic elastomer composition (B1) in the substrate layer was
changed to 80/20.
Comparative Example 5
[0200] A laminate film was prepared as in example 1 except that the
proportion of the 1-butene-.alpha.-olefin copolymer (A1) to the
propylenic elastomer composition (B2) in the substrate layer was
changed to 80/20.
Comparative Example 6
[0201] A laminate film was prepared as in example 1 except that the
proportion of the 1-butene-.alpha.-olefin copolymer (A1) to the
propylenic elastomer composition (B2) in the substrate layer was
changed to 20/80.
Comparative Example 7
[0202] A laminate film was prepared as in example 2 except that the
propylenic elastomer composition (B1) in the substrate layer was
replaced with an ethylene-.alpha.-olefin copolymer Tafmer P0275
(available from Mitsui Chemicals, Inc.).
Comparative Example 8
[0203] A laminate film was prepared as in example 2 except that the
propylenic elastomer composition (B1) in the substrate layer was
replaced with SEBS (registered trade mark: DYNARON DR8601P,
available from JSR Corporation).
Comparative Example 9
[0204] A laminate film was prepared as in example 2 except that the
propylenic elastomer composition (B1) in the substrate layer was
replaced with hydrogenated styrene-butadiene rubber (registered
trade mark: DYNARON DR1322P, available from JSR Corporation).
Comparative Example 10
[0205] A mixture (30/70 by mass) of homopolypropylene, h-PP
(available from Prime Polymer Co., Ltd. trade name F107PV) and
low-density polyethylene, LDPE (available from Prime Polymer Co.,
Ltd., trade name: Milason 11P) was extruded from an extruder
equipped with a flight screw at an extruding temperature of
230.degree. C. to yield a monolayer film.
Comparative Example 11
[0206] A mixture (30/10/60 by mass) of high-density polyethylene,
HDPE (available from Prime Polymer Co., Ltd., trade name Hi-Zex
2100J), ethylene-propylene rubber, EPR (available from Mitsui
Chemicals, Inc., trade name P0275), and random polypropylene, r-PP
(available from Prime Polymer Co., Ltd., trade name F327) was
extruded from an extruder equipped with a flight screw at an
extruding temperature of 230.degree. C. to yield a monolayer
film.
Comparative Example 12
[0207] A mixture (20/10/70 by mass) of homopolypropylene h-PP
(available from Prime Polymer Co., Ltd., trade name F107PV),
ethylene-propylene rubber, EPR (available from Mitsui Chemicals,
Inc., trade name P0275), and ethylene-methacrylic acid copolymer,
EMAA (DUPONT-MITSUI POLYCHEMICALS CO., LTD, trade name N1108C) was
extruded from an extruder equipped with a flight screw at an
extruding temperature of 230.degree. C. to yield a monolayer
film.
[0208] The films prepared in Examples and Comparative Examples were
subjected to evaluation of 1) expandability, 2) ease of necking,
and 3) handling performance, as described below. These films are
also subjected to evaluation of 4) adhesive force of the adhesive
layer, as described below. The films of some of the Examples were
subjected to 5) TEM observation.
[0209] 1) Expandability of Film
[0210] After the separator was detached from each film, the
adhesive layer of the film was put into tight contact with an
8-inch ring frame with a rubber roller. Non-adhesive films
(Examples 8 and 9, Comparative Examples 10, 11, and 12) were each
fixed to a ring frame with a double-sided adhesive tape (Nicetack,
Nichiban Co., Ltd.).
[0211] A Grid pattern consisting of 2-cm squares was written with a
permanent marker on the surface of the low-friction layer, which
enhanced slippage of the film. The grid pattern was 12 cm in length
in MD and TD directions. As shown in FIG. 6A, the ring frame 44 was
fixed to an expander such that the surface of the substrate layer
of the film 40 came into contact with the stage 43 of the expander.
The expander used was HS-1800 made by Hugle Electronics Inc.
[0212] As shown in FIG. 6B, the stage 43 of the expander was lifted
up by 65 mm to measure the lengths of the grid in the TD and MD
directions after the film 40 was expanded. The observed values were
inserted into the following equation to determine the expansion
rate and anisotropy of the expansion rate.
Expansion rate(MD and TD directions)(%)=100.times.(length of grid
after expansion)/(length of grid before expansion)
Anisotropy of expansion rate=Abs|(expansion rate in MD
direction)-(expansion rate in TD direction)|
[0213] This expansion rate indicates an expansion rate of the
expandable adhesive film on the stage. Since the stage was lifted
up by 65 mm for all the films as described above, a film having a
low expansion rate represents that was is not sufficiently expanded
on the stage but was expanded between the edges of the stage and
the ring frame. The expansion rate thus corresponds to
expandability required for dicing steps involving picking up of
semiconductor chips simulated by the grid pattern.
[0214] 2) Tendency to Necking
[0215] The tendency to necking of a film during expansion was
evaluated by the occurrence of clouding at a portion in contact
with a stage and a portion in contact with an edge of the stage in
accordance with the following ranks:
[0216] .largecircle.: No necking was observed
[0217] x: Necking was observed
[0218] 3) Handling Performance
[0219] The handling performance of the film was evaluated based on
the tensile modulus of a film. In detail, the film was cut into a
strip specimen having a width (TD direction) of 10 mm and a length
(MD direction) of 100 mm. The tensile modulus of the specimen was
measured with a tensilometer at a tensile rate of 300 min/min in
accordance with HS K7161 with a chuck-to-chuck distance of 50 mm.
The tensile modulus was the average of five specimens at a
temperature of 23.degree. C. and a humidity of 55% for each
film.
[0220] x: A tensile modulus of the overall film of less than 70 MPa
or more than 170
[0221] MPa.
[0222] .largecircle.: A tensile modulus of the overall film in the
range of 70 MPa to 170 MPa.
[0223] 4) Adhesive Force
[0224] The adhesive force of the resulting films (a coextruded film
with an adhesive layer, and a UV-curable film with an adhesive
layer) was measured at a temperature of 23.degree. C. and a
relative humidity of 50% in accordance with JIS Z0237. The films
were each bonded to a stainless steel-BA plate under a pressure of
about 2 kg with a rubber roller, and allowed to stand for 30
minutes in a constant environment at a temperature of 23.degree. C.
and a relative humidity of 50%. The adhesive force was then
measured when the film was peeled off from the stainless steel-BA
plate at a peeling rate of 300 mm/min in the direction
perpendicular to a surface of the plate. The measurement of the
adhesive force was repeated twice. The average measured for two
test pieces having a width of 25 mm was defined as "adhesive force
(N/25 nm)".
[0225] The low-friction layers, substrate layers, and adhesive
layers used in Examples and Comparative Examples were subjected to
determination of tensile modulus and MFR, in the manner described
above. In Tables, the term "tensile modulus (A/B)" indicates the
tensile modulus of the substrate layer. Table 4 shows the results
of Examples 1 to 6; Table 5 the results of Examples 7 to 12; and
Table 6 the results of Examples 13 to 18. Table 7 shows the results
of Comparative Examples 1 to 6; Table 8 the results of Comparative
Examples 7 to 9; and Table 9 the results of Comparative Examples 10
to 12.
TABLE-US-00004 TABLE 4 Example Example Example Example Example
Example 1 2 3 4 5 6 Sheet Low friction Type of resin Evolue Evolue
Evolue Evolue Evolue Evolue configuration layer SP2040 SP2040
SP2040 SP2040 SP2040 SP2040 Tensile modulus (MPa) 105 105 105 105
105 105 MFR at 230.degree. C. (g/10 min) 3.8 3.8 3.8 3.8 3.8 3.8
Thickness (.mu.m) 8 8 8 8 8 8 Substrate 1-Butene-.alpha.-olefin
copolymer (A) A1 A1 A1 A1 A1 A1 layer Tensile modulus (A) (MPa) 430
430 430 430 430 430 Density (kg/m.sup.3) 915 915 915 915 915 915
MFR at 230.degree. C. (g/10 min) 4.8 4.8 4.8 4.8 4.8 4.8 Propylenic
elastomer composition (B) B1 B1 B1 B2 B2 B2 Tensile modulus (B)
(MPa) 42 42 42 12 12 12 Density (kg/m.sup.3) 868 868 868 866 866
866 MFR at 230.degree. C. (g/10 min) 4 4 4 6 6 6 Mixing ratio A/B
60/40 50/50 40/60 60/40 50/50 40/60 Tensile modulus (A/B) (MPa) 275
236 197 263 221 179 Thickness (.mu.m) 64 60 64 64 64 64 Adhesive
Type of resin PN3560 PN3560 PN3560 PN3560 PN3560 PN3560 layer
Tensile modulus (MPa) 12 12 12 12 12 12 MFR at 230.degree. C. (g/10
min) 6 6 6 6 6 6 Adhesive force (N/25 mm) 3.0 3.0 3.0 3.0 3.0 3.0
Thickness (.mu.m) 12 12 12 12 12 12 Evaluation Expansion MD
direction (%) 132 135 133 128 142 129 rate TD direction (%) 130 132
135 127 142 130 Anisotropy (%) of expansion rate 2.0 3.0 2.0 1.0
0.0 1.0 Necking Portion in contact with Stage .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. Portion in contact with Edge of Stage .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. Handling Tensile modulus (MPa) 120 110 80 115 100 75
performance .smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle.
TABLE-US-00005 TABLE 5 Example Example Example Example Example
Example 7 8 9 10 11 12 Sheet Low friction Type of resin Evolue
Evolue Evolue Same as Same as Same as configuration layer SP2040
SP2040 SP2040 substrate substrate substrate Tensile modulus (MPa)
105 105 105 layer layer layer MFR at 230.degree. C. (g/10 min) 3.8
3.8 3.8 Thickness (.mu.m) 8 8 8 8 8 8 Substrate
1-Butene-.alpha.-olefin copolymer (A) A1 A1 A1 A1 A1 A1 layer
Tensile modulus (A) (MPa) 430 430 430 430 430 430 Density
(kg/m.sup.3) 915 915 915 915 915 915 MFR at 230.degree. C. (g/10
min) 4.8 4.8 4.8 4.8 4.8 4.8 Propylenic elastomer composition (B)
Synthesis B1 B2 B1 B1 B1 Example b1-4 Tensile modulus (B) (MPa) 10
42 12 42 42 42 Density (kg/m.sup.3) 860 868 866 868 868 868 MFR at
230.degree. C. (g/10 min) 5 4 6 4 4 4 Mixing ratio A/B 60/40 60/40
60/40 60/40 60/40 60/40 Tensile modulus (A/B) (MPa) 262 275 263 275
275 275 Thickness (.mu.m) 64 64 64 64 64 64 Adhesive Type of resin
Evolue Evolue Evolue PN3560 PN2060 DYNARON layer SP2040 SP2040
SP2040 DR1322P Tensile modulus (MPa) 105 105 105 12 25 1.8 MFR at
230.degree. C. (g/10 min) 3.8 3.8 3.8 6 6 4 Adhesive force (N/25
mm) No No No 6.0 4.0 1.8 adhesion adhesion adhesion Thickness
(.mu.m) 12 12 12 12 12 12 Evaluation Expansion MD direction (%) 125
132 129 139 139 129 rate TD direction (%) 127 129 128 139 140 129
Anisotropy (%) of expansion rate 2.0 3.0 1.0 0.0 1.0 0.0 Necking
Portion in contact with Stage .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. Portion in
contact with Edge of Stage .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. Handling
Tensile modulus (MPa) 128 134 124 123 123 122 performance
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle.
TABLE-US-00006 TABLE 6 Example Example Example Example Example
Example 13 14 15 16 17 18 Sheet Low friction Type of resin The same
NUCREL NUCREL NUCREL Same as Same as configuration layer as sub-
AN4213C N1108C AN4213C substrate substrate Tensile modulus (MPa)
strate 28 26 28 layer layer MFR at 230.degree. C. (g/10 min) layer
18 14 18 Thickness (.mu.m) 8 8 8 8 8 8 Substrate
1-Butene-.alpha.-olefin copolymer (A) A1 A1 A1 A1 A1 A1 layer
Tensile modulus (A) (MPa) 430 430 430 430 430 430 Density
(kg/m.sup.3) 915 915 915 915 915 915 MFR at 230.degree. C. (g/10
min) 4.8 4.8 4.8 4.8 4.8 4.8 Propylenic elastomer composition (B)
B1 B1 B1 B1 B3 B4 Tensile modulus (B) (MPa) 42 42 42 42 25 16
Density (kg/m.sup.3) 868 868 868 868 868 867 MFR at 230.degree. C.
(g/10 min) 4 4 4 4 4 4 Mixing ratio A/B 60/40 60/40 60/40 60/40
60/40 60/40 Tensile modulus (A/B) (MPa) 275 275 275 275 220 190
Thickness (.mu.m) 64 64 64 64 64 64 Adhesive Type of resin UV-
PN3560 PN3560 NUCREL PN3560 PN3560 layer curable AN4213C Tensile
modulus (MPa) 0.3 12 12 28 12 12 MFR at 230.degree. C. (g/10 min)
-- 6 6 18 6 6 Adhesive force (N/25 mm) 3.2 6.0 6.0 4.0 6.0 6.0
Thickness (.mu.m) 30 12 12 12 12 12 Evaluation Expansion MD
direction (%) 133 129 129 129 137 142 rate TD direction (%) 135 130
130 130 135 143 Anisotropy (%) of expansion rate 2.0 1.0 1.0 1.0
2.0 1.0 Necking Portion in contact with Stage .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. Portion in contact with Edge of Stage .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. Handling Tensile modulus (MPa) 110 115 124 122 110
106 performance .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle.
TABLE-US-00007 TABLE 7 Compar- Compar- Compar- Compar- Compar-
Compar- ative ative ative ative ative ative Example 1 Example 2
Example 3 Example 4 Example 5 Example 6 Sheet Low friction Type of
resin Evolue Evolue Evolue Evolue Evolue Evolue configuration layer
SP2040 SP2040 SP2040 SP2040 SP2040 SP2040 Tensile modulus (MPa) 19
19 19 19 19 19 MFR(g/10 min) 3.8 3.8 3.8 3.8 3.8 3.8 Thickness
(.mu.m) 8 8 8 8 8 8 Substrate 1-Butene-.alpha.-olefin copolymer A
A1 A2 A3 A1 A1 A1 layer Tensile modulus (A) (MPa) 430 200 180 430
430 430 Density (kg/m.sup.3) 915 900 900 915 915 915 MFR at
230.degree. C. (g/10 min) 4.8 10 8 4.8 4.8 4.8 Propylenic elastomer
composition B -- -- -- B1 B2 B2 Tensile modulus (B) (MPa) -- -- --
42 12 12 Density (kg/m.sup.3) -- -- -- 868 866 866 MFR at
230.degree. C. (g/10 min) -- -- -- 4 6 6 Mixing ratio A/B 100/0
100/0 100/0 80/20 80/20 20/80 Tensile modulus (A/B) (MPa) 430 180
200 352 346 96 Thickness (.mu.m) 60 60 60 64 64 64 Adhesive Type of
resin PN3560 PN3560 PN3560 PN3560 PN3560 PN3560 layer Tensile
modulus (MPa) 12 12 12 12 12 12 MFR (g/10 min) 6 6 6 6 6 6 Adhesive
force (N/25 mm) 3.0 3.0 3.0 3.0 3.0 3.0 Thickness (.mu.m) 12 12 12
12 12 12 Evaluation Expansion MD direction (%) 115 107 111 125 119
114 rate TD direction (%) 116 108 110 124 120 116 Anisotropy (%) of
expansion rate 1.0 1.0 1.0 1.0 1.0 2.0 Necking Portion in contact
with Stage x .smallcircle. .smallcircle. x x .smallcircle. Portion
in contact with Edge of Stage x .smallcircle. .smallcircle. x x
.smallcircle. Handling Tensile modulus (MPa) 200 130 140 170 145 30
performance x .smallcircle. .smallcircle. x .smallcircle. x
TABLE-US-00008 TABLE 8 Comparative Comparative Comparative Example
7 Example 8 Example 9 Sheet configuration Low friction Type of
resin Evolue Evolue Evolue layer SP2040 SP2040 SP2040 Tensile
modulus (MPa) 105 105 105 MFR(g/10 min) 3.8 3.8 3.8 Thickness
(.mu.m) 8 8 8 Substrate layer 1-Butene-.alpha.-olefin copolymer (A)
A1 A1 A1 Tensile modulus (A) (MPa) 430 430 430 Density (kg/m.sup.3)
915 915 915 MFR at 230.degree. C. (g/10 min) 4.8 4.8 4.8 Propylene
elastomer composition (B) P0275 DYNARON DYNARON DR8601P DR1322P
Tensile modulus (B) (MPa) 11 7 1.8 Density (kg/m.sup.3) 858-870 890
890 MFR at 230.degree. C. (g/10 min) 5.3 3.5 3.5 Mixing ratio A/B
50/50 50/50 50/50 Tensile modulus (A/B) (MPa) 220.5 218.5 215.9
Thickness (.mu.m) 68 68 68 Adhesive layer Type of resin PN3560
PN3560 PN3560 Tensile modulus (MPa) 12 12 12 MFR(g/10 min) 6 6 6
Adhesive force (N/25 mm) 3 3 3 Thickness (.mu.m) 12 12 12
Evaluation Expansion rate MD direction (%) 127 127 129 TD direction
(%) 120 147 129 Anisotropy (%) of expansion rate 7 20 0 Necking
Portion in contact with Stage .smallcircle. x x Portion in contact
with Edge of Stage x x .smallcircle. Handling Tensile modulus (MPa)
63 36 21 performance x x x
TABLE-US-00009 TABLE 9 Comparative Comparative Comparative Example
10 Example 11 Example 12 Sheet configuration Low friction Type of
resin -- -- -- layer Tensile modulus (MPa) -- -- -- MFR(g/10 min)
-- -- -- Thickness (.mu.m) -- -- -- Substrate layer Highly
crystalline polymer h-PP HDPE/EPR h-PP/EPR Tensile modulus (A)
(MPa) 1400 860/11 1400/11 Density (kg/m.sup.3) 910 956/858 910/858
MFR at 230.degree. C. (g/10 min) 7.0 6.0/5.3 7.6/5.3 Lowly
crystalline polymer LDPE r-PP EMAA Tensile modulus (B) (MPa) 140
820 26 Density (kg/m.sup.3) 917 910 940 MFR at 230.degree. C. (g/10
min) 7.0 7.8 8.0 Highly crystalline polymer/Lowly 30/70 30/10/60
20/10/70 crystalline polymer Tensile modulus (A/B) (MPa) 518 751
290 Thickness (.mu.m) 100 100 100 Adhesive layer Type of resin --
-- -- Tensile modulus (MPa) -- -- -- MFR (g/10 min) -- -- --
Adhesive force (N/25 mm) -- -- -- Thickness (.mu.m) -- -- --
Evaluation Expansion rate MD direction (%) Ruptured Ruptured
Ruptured TD direction (%) Ruptured Ruptured Ruptured Anisotropy (%)
of expansion rate Unevaluable Unevaluable Unevaluable Necking
Portion in contact with Stage Unevaluable Unevaluable Unevaluable
Portion in contact with Edge of Unevaluable Unevaluable Unevaluable
Stage Handling Tensile modulus (MPa) 270 420 200 performance x x
x
[0226] The films in Examples 1 to 18, having substrate layers
prepared by blending of a specific 1-butene-.alpha.-olefin
copolymer (A) and a specific propylenic elastomer composition (B)
in a predetermined ratio, each exhibit a high expansion rate of
120% or more and no necking. In contrast, the films in Comparative
Examples 1 to 3, not containing specific propylenic elastomer
composition (B) and the films in Comparative Examples 4 to 6, where
the ratio of the 1-butene-.alpha.-olefin copolymer (A) to the
propylenic elastomer composition (B) is outside the present
invention, exhibit low expansion rate, poor handling performance,
or tendency to necking. The films in Comparative Examples 7 to 9,
the propylenic elastomer composition (B) was replaced with any
other elastomer, exhibit satisfactory expandability, but exhibit
tendency to necking or poor handling performance. The films in
Comparative Examples 10 to 12 were ruptured during the expansion
test, indicating significantly low expandability.
Example 19
Preparation of Materials for Individual Layers
[0227] A blend of a 1-butene-.alpha.-olefin copolymer (A1) and a
propylenic elastomer composition (B1) in a mass ratio of 60/40 was
prepared as a raw material for a substrate layer. TAFMER P0275
(registered trade mark) available from Mitsui Chemicals, Inc. was
prepared as a raw material for an intermediate layer. The
UV-curable adhesive coating solution described above was prepared
as a raw material for an adhesive layer. A blend the same as that
for the substrate layer was prepared as a raw material for a
low-friction layer.
[0228] Formation of Dicing Film
[0229] The raw materials for the substrate layer, intermediate
layer, and low-friction layer were each melt-kneaded in an extruder
equipped with a full-flight screw. These three melted resins were
coextruded from a multilayer die at an extrusion temperature of
230.degree. C. for the substrate layer, intermediate layer, and
low-friction layer into a triple-layer laminate. An adhesive layer
was laminated onto the intermediate layer as in the manner for
lamination of a UV adhesive layer in Example 13 to form a
four-layered laminate film (dicing film) including the low-friction
layer, substrate layer, intermediate layer, and adhesive layer in
this order as shown in FIG. 3. In the dicing film, the low-friction
layer, substrate layer, intermediate layer, and adhesive layer have
thicknesses of 10 .mu.m, 60 .mu.m, 350 .mu.m, and 5 .mu.m,
respectively.
Examples 20 and 21
[0230] Dicing films were formed as in Example 19, except that the
blend ratio of the 1-butene-.alpha.-olefin copolymer (A1) to the
propylenic elastomer composition (B1) in the substrate layer was
changed as shown in Table 10.
Example 22
[0231] A dicing film was formed as in Example 19, except that the
propylenic elastomer composition (B1) for the substrate layer was
replaced with a propylenic elastomer composition (B2).
Example 23
[0232] A dicing film was formed as in Example 19, except that the
propylenic elastomer composition (B1) for the substrate layer was
replaced with a propylenic elastomer composition (B3).
Example 24
[0233] A dicing film was formed as in Example 19, except that the
propylenic elastomer composition (B1) for the substrate layer was
replaced with a propylenic elastomer composition (B4).
Example 25
[0234] A dicing film was formed as in Example 19, except that the
material for the low-friction layer was changed to a linear
low-density polyethylene, trade name Evolue SP2040 (available from
Prime Polymer Co., Ltd., Vicat softening point: 101.degree. C.),
the extrusion temperature of the substrate layer, intermediate
layer, adhesive layer, and low-friction layer was 230.degree. C.,
and four melted resins were laminated by coextrusion through a
multilayer die. In the dicing film, the thicknesses of the
low-friction layer, substrate layer, intermediate layer, and
adhesive layer were 10 .mu.m, 60 .mu.m, 350 .mu.m, and 5
respectively.
Example 26
[0235] A dicing film was formed as in Example 25, except that the
material for the low-friction layer was changed to a mixture of
low-density polyethylene (available from DUPONT-MITSUI
POLYCHEMICALS CO., LTD., trade name: Milason 11P) and 5 wt %
silicone resin (available from Dow Corning Toray Co., Ltd., trade
name BY27-002).
Example 27
[0236] A dicing film was formed as in Example 25, except that the
material for the intermediate layer was changed to TAFMER P0280
(registered trade mark) available from Mitsui Chemicals, Inc.
Example 28
[0237] A dicing film was formed as in Example 25, except that the
material for the adhesive layer was changed to NOTIO PN3560 (trade
name, available from Mitsui Chemicals, Inc., MFR: 4 g/10 min at a
temperature of 230.degree. C. in accordance with ASTM D1238).
Example 29
[0238] A dicing film was formed as in Example 25, except that the
material for the adhesive layer was changed to NOTIO PN2060 (trade
name, available from Mitsui Chemicals, Inc., MFR: 7 g/10 min at a
temperature of 230.degree. C. in accordance with ASTM D1238).
Example 30
[0239] A dicing film was formed as in Example 25, except that the
material for the adhesive layer was changed to a hydrogenated
styrene-butadiene rubber (HSBR), Dynaron DR1322P (registered trade
mark, available from JSR Corporation).
Comparative Example 13
[0240] A dicing film was formed as in EXAMPLE 25, except that the
material for the substrate layer was composed of only the
1-butene-.alpha.-olefin copolymer (A1).
Comparative Example 14
[0241] A dicing film was formed as in Example 25, except that the
ratio of the 1-butene-.alpha.-olefin copolymer (A1) to the
propylenic elastomer composition (B1) in the substrate layer was
changed to 80/20.
Comparative Example 15
[0242] A dicing film was formed as in Example 25, except that the
ratio of the 1-butene-.alpha.-olefin copolymer (A1) to the
propylenic elastomer composition (B1) in the substrate layer was
changed to 20/80.
Comparative Example 16
[0243] A dicing film was formed as in Example 19, except that a
polyethylene terephthalate layer with a thickness of 75 .mu.m was
used as the substrate layer, and the low-friction layer was not
laminated.
Comparative Example 17
[0244] A dicing film was formed as in Example 25, except that an
ethylene-vinyl acetate (EVA) copolymer layer with a thickness of 60
.mu.m was used as the substrate layer.
Example 31
[0245] A dicing film was formed as in Example 25, except that an
ethylene-vinyl acetate (EVA) copolymer layer with a thickness of
350 .mu.m was used as the intermediate layer.
Example 32
[0246] A dicing film was formed as in Example 25, except that the
adhesive layer was not laminated.
Example 33
[0247] A dicing film was formed as in Example 10, except that the
thickness of the substrate layer was changed to 60 .mu.m.
Example 34
[0248] A dicing film was formed as in Example 33, except that the
propylenic elastomer composition (B1) for the substrate layer was
replaced with a propylenic elastomer composition (B5).
Example 35
[0249] A dicing film was formed as in Example 33, except that the
propylenic elastomer composition (B1) for the substrate layer was
replaced with a propylenic elastomer composition (B6).
Example 36
[0250] A dicing film was formed as in Example 33, except that the
propylenic elastomer composition (B1) for the substrate layer was
replaced with a propylenic elastomer composition (B7).
Example 37
[0251] A dicing film was formed as in Example 33, except that the
propylenic elastomer composition (B1) of the substrate layer was
replaced with a propylenic elastomer composition (B 8).
Comparative Example 18
[0252] A dicing film was formed as in Example 33, except that the
propylenic elastomer composition (B1) for the substrate layer was
replaced with a propylenic elastomer composition (B9).
Reference Example 1
[0253] The dicing film in Example 25 was subjected to irregularity
absorption evaluation (described below) at a table temperature of
25.degree. C., a roller temperature of 25.degree. C., and a
pressure of 0.5 MPa.
Reference Example 2
[0254] The dicing film in Example 25 was subjected to irregularity
absorption evaluation (described below) at a table temperature of
60.degree. C., a roller temperature of 60.degree. C., and a
pressure of 0.2 MPa.
Reference Example 3
[0255] A dicing film was formed as in Example 25, except that the
thickness of the intermediate layer of the dicing film was changed
to 180 .mu.m.
[0256] Evaluation of Dicing Film
[0257] For Examples 19 to 31, Comparative Examples 13 to 17, and
Reference Examples 1 to 3, the adhesive force to a ring frame,
irregularity absorption, and expandability was determined. The
tensile modulus, MFR, density, and adhesive force of individual
layers and materials constituting the layers were also measured as
in Examples 1 to 18. For the intermediate layer, the tensile
modulus E(25) at 25.degree. C. and the tensile modulus E(60) at
60.degree. C. were measured, and the ratio (E(60)/E(25)) of the
E(60) at 60.degree. C. to the E(25) at 25.degree. C. was
calculated.
[0258] For Examples 33 to 37 and Comparative Example 18, the
resulting films were subjected to evaluation of 1) expandability,
2) tendency to necking, and 3) handling performance, and 4)
adhesive force of the adhesive layer, as in Examples 1 to 18.
[0259] 1) Adhesiveness to Ring Frame
[0260] The adhesiveness of each film to a ring frame made by DISCO
Corporation was measured. In detail, the adhesive force of the
resulting dicing film to the ring frame was measured at a
temperature of 23.degree. C. and a relative humidity of 50% by the
testing method of pressure-sensitive adhesive tapes and sheets in
accordance with JIS Z0237. The dicing film was placed on the ring
frame on the adhesive layer side, was bonded to the ring frame
under a pressure of about 2 kg with a rubber roller, and was
allowed to stand for 30 minutes under a constant environment at a
temperature of 23.degree. C. and a relative humidity of 50%. The
adhesive force was determined when the dieing film was peeled off
from the ring frame at a peeling rate of 300 min/min in the
direction perpendicular to a surface of the ring frame. The
measurement of the adhesive force was repeated twice. The average
measured for two test samples was defined as "adhesive force (N) to
ring frame". An adhesive force of 0.1 N or more to the ring frame
was evaluated as .largecircle., an adhesive force of less than 0.1N
as x.
[0261] 2) Undulation Embedment
[0262] A wafer (made by Well, JCHIP10) provided with solder balls
having a diameter of 200 on a face provided with circuits was
prepared. A dicing film was bonded to the DISCO ring frame and the
wafer with a wafer mounter (made by Technovision, Inc., FMP-1143)
at a table temperature of 60.degree. C., a roller temperature of
25.degree. C., a pressure of 0.5 MPa, and a lamination rate of 2
mm/sec. The face provided with circuits after bonding the dicing
film was observed with a microscope (made by Keyence Corporation)
at a magnification of 50 to 200. Samples having gaps between the
irregularities on the patterned side and the dicing film were
evaluated as x, and samples with no gap were evaluated as
.largecircle..
[0263] 3) Expandability
[0264] The adhesive layer of the dicing film was put into close
contact with the ring frame with a rubber roller. The non-adhesive
dicing film (Comparative Example 19) was fixed to the ring frame
with a double-sided adhesive tape (NICHIBAN Co., Ltd., Nicetack). A
grid pattern consisting of 2-cm squares was written on the surface
of the adhesive layer of the dicing film with a permanent marker.
As shown in FIG. 6A, the ring frame 44 was fixed to an expander
such that the surface of the substrate layer of the dicing film 40
came into contact with the stage 43 of the expander. The expander
used was HS-1800 made by Hugle Electronics Inc.
[0265] As shown in FIG. 6B, the stage 43 of the expander was lifted
up by 65 mm to measure the lengths of the grid in the TD and MD
directions after the film 40 was expanded. The observed values were
inserted into the following equation to determine the expansion
rate and anisotropy of the expansion rate.
Expansion rate(MD and TD directions)(%)=100.times.(length of grid
after expansion)/(length of grid before expansion)
[0266] Samples having an expansion rate of 120% or more were
evaluated as 0, and samples having an expansion rate of less than
120% as x.
[0267] The results in Examples 19 to 24 are shown in Table 10; the
results in Examples 25 to 30 in Table 11; the results in
Comparative Examples 13 to 17 in Table 12; the results in Examples
31, 32, and Reference Examples 1 to 3 in Table 13; and the results
in Examples 33 to 37 and Comparative Example 18 in Table 14
TABLE-US-00010 TABLE 10 Example Example Example Example Example
Example 19 20 21 22 23 24 Sheet Low-friction Type of resin Same as
Same as Same as Same as Same as Same as configuration layer MFR at
230.degree. C. (g/10 min) substrate substrate substrate substrate
substrate substrate layer layer layer layer layer layer Thickness
(.mu.m) 10 10 10 10 10 10 Substrate 1-Butene-.alpha.-olefin
copolymer (A) A1 A1 A1 A1 A1 A1 layer Tensile modulus (A) (MPa) 430
430 430 430 430 430 Density (kg/m.sup.3) 915 915 915 915 915 915
MFR at 230.degree. C. (g/10 min) 4.8 4.8 4.8 4.8 4.8 4.8 Propylenic
elastomer composition (B) B1 B1 B1 B2 B3 B4 Tensile modulus (B)
(MPa) 42 42 42 12 25 16 Density (kg/m.sup.3) 868 868 868 866 868
867 MFR at 230.degree. C. (g/10 min) 4 4 4 6 4 4 Mixing ratio A/B
60/40 50/50 40/60 60/40 60/40 60/40 Tensile modulus (A/B) (MPa) 275
236 197 275 220 190 Thickness (.mu.m) 60 60 60 60 60 60
Intermediate Material TAFMER TAFMER TAFMER TAFMER TAFMER TAFMER
layer P0275 P0275 P0275 P0275 P0275 P0275 Density (kg/m.sup.3) 861
861 861 861 861 861 MFR at 230.degree. C. (g/10 min) 5.3 5.3 5.3
5.3 5.3 5.3 Tensile modulus E(25) (MPa) 5.5 5.5 5.5 5.5 5.5 5.5
Tensile modulus E(60) (MPa) 0.16 0.16 0.16 0.16 0.16 0.16
E(60)/E(25) 0.029 0.029 0.029 0.029 0.029 0.029 Thickness (.mu.m)
350 350 350 350 350 350 Adhesive Material UV UV UV UV UV UV layer
adhesion adhesion adhesion adhesion adhesion adhesion Adhesive
force (N/25 mm) 7 7 7 7 7 7 MFR at 230.degree. C. (g/10 min) -- --
-- -- -- -- Thickness (.mu.m) 5 5 5 5 5 5 Bonding Bonding
temperature (.degree. C.) 60 60 60 60 60 60 condition Bonding
pressure (MPa) 0.5 0.5 0.5 0.5 0.5 0.5 Wafer Height of
irregularities (.mu.m) 200 200 200 200 200 200 Evaluation Adhesion
to ring frame .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. results Undulation
embedment .smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. Expandability (>120%) .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle.
TABLE-US-00011 TABLE 11 Example Example Example Example Example
Example 25 26 27 28 29 30 Sheet Low friction Type of resin Evolue
Milason 11P + Evolue Evolue Evolue Evolue configuration layer
SP2040 BY27-002 (5 wt %) SP2040 SP2040 SP2040 SP2040 MFR at
230.degree. C. (g/10 min) 3.8 6.0 3.8 3.8 3.8 3.8 Thickness (.mu.m)
10 10 10 10 10 10 Substrate 1-Butene-.alpha.-olefin copolymer (A)
A1 A1 A1 A1 A1 A1 layer Tensile modulus (A) (MPa) 430 430 430 430
430 430 Density (kg/m.sup.3) 915 915 915 915 915 915 MFR at
230.degree. C. (g/10 min) 4.8 4.8 4.8 4.8 4.8 4.8 Propylenic
elastomer composition (B) B1 B1 B1 B1 B1 B1 Tensile modulus (B)
(MPa) 42 42 42 42 42 42 Density (kg/m.sup.3) 868 868 868 868 868
868 MFR at 230.degree. C. (g/10 min) 4 4 4 4 4 4 Mixing ratio A/B
60/40 60/40 60/40 60/40 60/40 60/40 Tensile modulus (A/B) (MPa) 275
275 275 275 275 275 Thickness (.mu.m) 60 60 60 60 60 60
Intermediate Material TAFMER TAFMER TAFMER TAFMER TAFMER TAFMER
layer P0275 P0275 P0280 P0275 P0275 P0275 Density (kg/m.sup.3) 861
861 869 861 861 861 MFR at 230.degree. C. (g/10 min) 5.3 5.3 5.3
5.3 5.3 5.3 Tensile modulus E(25) (MPa) 5.5 5.5 9.6 5.5 5.5 5.5
Tensile modulus E(60) (MPa) 0.16 0.16 0.24 0.16 0.16 0.16
E(60)/E(25) 0.029 0.029 0.025 0.029 0.029 0.029 Thickness (.mu.m)
350 350 350 350 350 350 Adhesive Material UV UV UV Notio Notio
DYNARON layer adhesion adhesion adhesion PN3560 PN2060 DR1322P
Adhesive force (N/25 mm) 7 7 7 6 4 1.8 MFR at 230.degree. C.(g/10
min) -- -- -- 6 6 4 Thickness (.mu.m) 5 5 5 5 5 5 Bonding Bonding
temperature (.degree. C.) 60 60 60 60 60 60 condition Bonding
pressure (MPa) 0.5 0.5 0.5 0.5 0.5 0.5 Wafer Height of
irregularities (.mu.m) 200 200 200 200 200 200 Evaluation Adhesion
to ring frame .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. results Undulation
embedment .smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. Expandability (>120%) .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle.
TABLE-US-00012 TABLE 12 Compar- Compar- Compar- Compar- Compar-
ative ative ative ative ative Example 13 Example 14 Example 15
Example 16 Example 17 Sheet Low-friction Type of resin Evolue
Evolue Evolue None Evolue configuration layer SP2040 SP2040 SP2040
SP2040 MFR at 230.degree. C. (g/10 min) 3.8 3.8 3.8 3.8 Thickness
(.mu.m) 5 5 5 -- 5 Substrate 1-Butene-.alpha.-olefin copolymer (A)
A1 A1 A1 PET EVA layer Tensile modulus (A) (MPa) 430 430 430 4000
9.5 Density (kg/m.sup.3) 915 915 915 1270 960 MFR at 230.degree. C.
(g/10 min) 4.8 4.8 4.8 -- 30 Propylenic elastomer composition (B)
None B1 B2 None None Tensile modulus (B) (MPa) -- 42 12 -- --
Density (kg/m.sup.3) -- 868 866 -- -- MFR at 230.degree. C. (g/10
min) -- 4 6 -- -- Mixing ratio A/B 100/0 80/20 20/80 100/0 100/0
Tensile modulus (A/B) (MPa) -- 352 96 -- -- Thickness (.mu.m) 60 60
60 75 60 Intermediate Material TAFMER TAFMER TAFMER TAFMER TAFMER
layer P0275 P0275 P0275 P0275 P0275 Density (kg/m.sup.3) 861 861
861 861 861 MFR at 230.degree. C. (g/10 min) 5.3 5.3 5.3 5.3 5.3
Tensile modulus E(25) (MPa) 5.5 5.5 5.5 5.5 5.5 Tensile modulus
E(60) (MPa) 0.16 0.16 0.16 0.16 0.16 E(60)/E(25) 0.029 0.029 0.029
0.029 0.029 Thickness (.mu.m) 350 350 350 350 350 Adhesive Material
UV UV UV UV UV layer adhesion adhesion adhesion adhesion adhesion
Adhesive force (N/25 mm) 7 7 7 7 7 MFR at 230.degree. C. (g/10 min)
-- -- -- -- -- Thickness (.mu.m) 5 5 5 5 5 Bonding Bonding
temperature (.degree. C.) 60 60 60 60 60 condition Bonding pressure
(MPa) 0.5 0.5 0.5 0.5 0.5 Wafer Height of irregularities (.mu.m)
200 200 200 200 200 Evaluation Adhesion to ring frame .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. results
Undulation embedment .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. Expandability (>120%) x x x x x
TABLE-US-00013 TABLE 13 Example Example Reference Reference
Reference 31 32 Example 1 Example 2 Example 3 Sheet Low-friction
Type of resin Evolue Evolue Evolue Evolue Evolue configuration
layer SP2040 SP2040 SP2040 SP2040 SP2040 MFR at 230.degree. C.
(g/10 min) 3.8 3.8 3.8 3.8 3.8 Thickness (.mu.m) 5 5 5 5 5
Substrate 1-Butene-.alpha.-olefin copolymer (A) A1 A1 A1 A1 A1
layer Tensile modulus (A) (MPa) 430 430 430 430 430 Density
(kg/m.sup.3) 915 915 915 915 915 MFR at 230.degree. C. (g/10 min)
4.8 4.8 4.8 4.8 4.8 Propylenic elastomer composition (B) B1 B1 B1
B1 B1 Tensile modulus (B) (MPa) 42 42 42 42 42 Density (kg/m.sup.3)
868 868 868 868 868 MFR at 230.degree. C. (g/10 min) 4 4 4 4 4
Mixing ratio A/B 60/40 60/40 60/40 60/40 60/40 Tensile modulus
(A/B) (MPa) 275 275 275 275 275 Thickness (.mu.m) 60 60 60 60 60
Intermediate Material EVA TAFMER TAFMER TAFMER TAFMER layer P0275
P0275 P0275 P0275 Density (kg/m.sup.3) 960 861 861 861 861 MFR at
230.degree. C. (g/10 min) 30 5.3 5.3 5.3 5.3 Tensile modulus E(25)
(MPa) 9.5 5.5 5.5 5.5 5.5 Tensile modulus E(60) (MPa) 1.2 0.16 0.16
0.16 0.16 E(60)/E(25) 0.126 0.029 0.029 0.029 0.029 Thickness
(.mu.m) 350 350 350 350 180 Adhesive Material UV None UV UV UV
layer adhesion adhesion adhesion adhesion Adhesive force (N/25 mm)
7 Non- 7 7 7 adhesive MFR at 230.degree. C. (g/10 min) -- -- -- --
-- Thickness (.mu.m) 5 -- 5 5 5 Bonding Bonding temperature
(.degree. C.) 60 60 25 60 60 condition Bonding pressure (MPa) 0.5
0.5 0.5 0.2 0.5 Wafer Height of irregularities (.mu.m) 200 200 200
200 200 Evaluation Adhesion to ring frame .smallcircle. x
.smallcircle. .smallcircle. .smallcircle. Results Undulation
embedment x .smallcircle. x x x Expandability (>120%)
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle.
TABLE-US-00014 TABLE 14 Compar- Example Example Example Example
Example ative 33 34 35 36 37 Example 18 Sheet Low friction Type of
resin The same The same The same The same The same The same
configuration layer Tensile modulus (MPa) as sub- as sub- as sub-
as sub- as sub- as sub- MFR at 230.degree. C. (g/10 min) strate
strate strate strate strate strate layer layer layer layer layer
layer Thickness (.mu.m) 8 8 8 8 8 8 Substrate
1-Butene-.alpha.-olefin copolymer (A) A1 A1 A1 A1 A1 A1 layer
Tensile modulus (A) (MPa) 430 430 430 430 430 430 Density
(kg/m.sup.3) 915 915 915 915 915 915 MFR at 230.degree. C. (g/10
min) 4.8 4.8 4.8 4.8 4.8 4.8 Propylenic elastomer composition (B)
B1 B5 B6 B7 B8 B9 Tensile modulus (B) (MPa) 42 60 90 160 420 700
Density (kg/m.sup.3) 868 866 868 867 867 867 MFR at 230.degree. C.
(g/10 min) 4 6 6 7 7 7 Mixing ratio A/B 50/50 50/50 50/50 50/50
50/50 50/50 Tensile modulus (A/B) (MPa) 236 245 260 295 435 570
Thickness (.mu.m) 60 60 60 60 60 60 Adhesive Type of resin PN3560
PN3560 PN3560 PN3560 PN3560 PN3560 layer Tensile modulus (MPa) 12
12 12 12 12 12 MFR at 230.degree. C. (g/10 min) 6 6 6 6 6 6
Adhesive force (N/25 mm) 6 6 6 6 6 6 Thickness (.mu.m) 12 12 12 12
12 12 Evaluation Expansion MD direction (%) 139 142 139 129 120
Fractured rate TD direction (%) 139 142 138 127 118 Fractured
Anisotropy (%) of expansion rate 0 0 1.2 1.4 2.3 Unevalu- able
Necking (Face on stage) .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. Unevalu- able (At periphery of stage)
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. Unevalu- able Handling Tensile modulus (MPa) 123 125
128 145 168 210 performance Evaluation .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. x
[0268] The films in Examples 19 to 32, having substrate layers
prepared by blend of a specific 1-butene-.alpha.-olefin copolymer
(A) and a specific propylenic elastomer composition (B) in a
predetermined ratio, each exhibit a high expansion rate of 120% or
more. In contrast, the films in Comparative Example 13, not
containing the specific propylenic elastomer composition (B), and
the film in Comparative Examples 14 and 15, where the ratio of the
1-butene-.alpha.-olefin copolymer (A) to the propylenic elastomer
composition (B) is outside the present invention, each exhibit a
low expansion rate. The films in Comparative Examples 16 and 17,
not containing the specific 1-butene-.alpha.-olefin copolymer (A)
and the specific propylenic elastomer composition (B), each exhibit
a low expansion rate.
[0269] The intermediate layer disposed between the substrate layer
and the adhesive layer, satisfying the relation: E(60)/E(25)<0.1
where E(25) is tensile modulus at 25.degree. C. and E(60) is
tensile modulus at 60.degree. C. and having a tensile modulus E(25)
at 25.degree. C. of 1 to 10 MPa improves irregularity absorption
(Examples 19 to 30 and 32). In contrast, Example 31 not satisfying
the relation: E(60)/E(25)<0.1 exhibits poor irregularity
absorption.
[0270] The adhesive layer having predetermined adhesive force
achieves tight contact to the ring frame (Examples 19 to 30). In
contrast, the film not provided with an adhesive layer (Example 32)
exhibits low adhesive force to the ring frame.
[0271] Reference Example 1 indicates the dicing film in Example 25
bonded to a wafer at a temperature less than that specified in the
method of manufacturing a semiconductor device of the present
invention. Because of insufficient melting of the intermediate
layer, irregularity absorption is insufficient. Reference Example 2
indicates the dicing film in Example 25 bonded to a wafer under a
pressure less than that specified in the method of manufacturing a
semiconductor device of the resent invention. Because of
insufficient melting of the intermediate layer and the adhesive
layer, irregularity absorption is insufficient. Reference Example 3
indicates the dicing film in Example 25 including an intermediate
layer having a thickness less than the height of irregularities on
the wafer. Because of insufficient melting of the intermediate
layer and the adhesive layer, irregularity absorption is
insufficient.
[0272] The dicing films in Examples 33 to 37 containing 70 weight
parts or less of polypropylene (b2) relative to 100 weight parts of
propylenic elastomer composition (B) exhibit superior handling
performance without necking. The expansion rate, however, decreases
in the MD and TD directions as the amount of the polypropylene (b2)
increases. The anisotropy of the expansion rate also increases with
increasing amount. The dicing film in Comparative Example 18
containing the propylenic elastomer composition (B) having a
tensile modulus exceeding 500 MPa is ruptured due to insufficient
expansion.
INDUSTRIAL APPLICABILITY
[0273] The present invention provides an olefinic expandable
substrate and a dicing film that exhibits less contamination, high
expandability and less necking, which cannot be achieved by
conventional olefinic expandable substrates.
REFERENCE SIGNS LIST
[0274] 10, 30, 40, 50: dicing film [0275] 12, 32, 52: substrate
layer [0276] 13, 53: intermediate layer [0277] 14, 34, 54: adhesive
layer [0278] 16, 36, 56: low-friction layer [0279] 22, 42: wafer
[0280] 43: stage [0281] 44: ring frame
* * * * *